'Worst-Case Scenario' Averted With Orange County Chemical Tank, Evacuation Zone Shrinks

GARDEN GROVE, CA — Thousands of residents were returning to their homes Monday evening as officials said a "catastrophic worst-case scenario" explosion of a 7,000-gallon chemical tank in Orange County has been averted.

"We are happy to report that the most catastrophic and worst-case scenario was mitigated and resolved," Orange County Fire Authority Interim Fire Chief TJ McGovern said Monday evening during a news briefing.

He said the elimination of the threat of the boiling-liquid-expanding-vapor explosion of the tank filled with toxic methyl methacrylate is just the start of what needs to be done.

"I want to reinforce it's not over yet," he said. "We still have work to do."

That included setting up the new, reduced evacuation zone. McGovern said the new zone is bounded by Orangewood Avenue to the north, Dale Street to the east, Knott Street to the west and Garden Grove Boulevard to the south. Traffic has resumed east and west on Garden Grove Boulevard, he said.

That leaves about 16,000 people out of the initial 50,000 still under evacuation orders, McGovern said.

Orange County Fire Authority Division Chief Craig Covey reiterated what he said at the morning briefing, saying a crack in the tank had formed. The crack, however, was just enough to release the pressure without causing a leak or explosion.

He said he understood the frustrations of residents waiting to find out when they would be able to return to their homes, but said monitoring the tank had to be done at times it put the firefighters at the least possible risk.

"That tank was ready to blow up," Covey said. "We were not putting firefighters down range into the area during the daylight when the tank is at its most vulnerability."

But as they monitored the temperature and removed the insulation to pour water directly on the tank to cool it, they saw the temperature begin to trend down, Covey said.

"What we essentially were shooting for in layman's terms is to boil an egg," he said. "You have to control that temperature to get that egg done right and not crack the shell."

Covey said the experts believe the liquid inside the tank has hardened and that an explosion is unlikely, but they are maintaining the smaller evacuation area while they continue to evaluate and address the situation.

For those residents who were able to go home, authorities said there are no risks of toxic chemical exposure at their homes.

More than 50,000 county residents remained evacuated as Memorial Day weekend wore on and the tank filled with toxic methyl methacrylate continued to be a threat to the community in Garden Grove.

"You can feel safe there was no contamination," said Dr. Regina Chinsio-Kwong, the Orange County publie health officer. "I want to reassure everyone who is outside of the new evacuation zone that when you go home, you can feel safe there was no contamination.

"There were no fumes, there were no vapors from this, you should feel comfortable going home even if you are across the street from the new evacuation zone," she said.

Garden Grove Mayor Stephanie Klopfenstein said the city's response won't end once everyone goes home.

"We will make sure this incident is fully reviewed," she said. There will be a special meeting at the community meeting center Tuesday at 5:30 p.m. "focused on the incident, the city's response and the latest information available."

Gov. Gavin Newsom proclaimed a state of emergency on Saturday, and requested a federal emergency declaration from Trump one day later. Trump signed the order Monday, according to Newsom and other local officials.

"I'm proud to announce that President Trump heard our request and signed a federal emergency declaration for Orange County and our ongoing hazmat situation. Thank you, Mr. President!'' Orange County Supervisor Janet Nguyen posted on X.

The governor's office said a declaration from the Trump administration will permit federal cost-sharing support for urgent actions such as evacuations, sheltering and emergency medical support, access to public assistance to help pay for overtime, equipment and other emergency actions, and the ability for FEMA to provide additional direct federal assistance, such as personnel, specialized equipment and technical support.

GKN Aerospace, the company that operates the facility where the tank is located, posted the following statement on its website Monday:

"During the evening of May 24, technical specialists working for the GKN Aerospace facility in Garden Grove conducted a joint operation with Orange County Fire Authority to assess the storage tank more closely. The team safely and successfully removed external insulation material from the tank in order to help advance efforts to cool its contents. This operation followed several days of careful monitoring and work to stabilize the tank, in conjunction with the dedicated team of experts on-site.

"We are continuing to work around the clock with the OCFA, the EPA and all relevant federal, state and local agencies to mitigate the ongoing risk of a leak. We remain extremely thankful for their dedication and hard work.

"We apologize for the ongoing disruption this incident is causing and our priority remains its safe resolution, so that residents can return to their homes as quickly as possible. Please continue to follow all instructions issued by local authorities and emergency personnel at this time."

McGovern said in a social media video update Sunday night that officials would be conducting an all-night mission to confirm that the pressure in the tank had been released and that the threat of a "worst-case catastrophic event" had been eliminated.

"We are not there yet," he said Sunday night. "We need to run this operation tonight. Please help us. Stay out of the evacuation zone, let us run our operation."

"There is one known crack on the tank," the OCFA reported on X at 9:35 p.m. Sunday. "There is also peeling of the weather stripping on the exterior, but this is not an additional crack. There is currently no active leak."

"We are conducting an all-night mission in order to confirm the pressure in the tank has been released and that the BLEVE threat has been eliminated," McGovern told reporters Sunday night.

BLEVE is an acronym for Boiling-Liquid-Expanding-Vapor Explosion, according to the American Institute of Chemical Engineers.

"The BLEVE threat is the worst-case catastrophic event that we've been talking about," McGovern said.

Meanwhile, Newsom's Office announced that nearly 800 state and local first responders and emergency personnel were supporting public safety, evacuations, traffic management, sheltering operations, environmental monitoring and community assistance efforts.

"California is mobilizing every available resource to protect impacted communities and support local response efforts. We are working hand-in-hand with local officials and emergency personnel to keep people safe, support evacuations and sheltering operations, monitor environmental conditions and ensure communities receive timely and accurate information," a statement from the governor's office read.

McGovern had previously announced late Sunday morning that firefighters acting on a plan developed Saturday by a specialized team of experts had seen the tank and discovered the possible crack, which could be relieving pressure. Officials were working Sunday to vet and validate information, McGovern said, adding the new development could change the trajectory and strategy of the situation.

A crack could be a welcome development, as it could mean product or pressure inside the tank is being released, reducing the chance the tank explodes, said Andrew Whelton, an engineering professor at Purdue University.

Orange County Fire Authority Capt. Wayhowe Huang told The Associated Press on Sunday that it did not appear that any of the highly volatile chemicals in the tank had leaked.

“There’s still the danger of a possible explosion," Huang said Sunday.

The inside of the tank reached 100 degrees Sunday, Democratic state Sen. Tom Umberg said, an increase of 10 degrees since Saturday.

In updates Saturday afternoon and evening, officials reported that while air monitoring remained normal and experts across the state had been brought in to brainstorm potential solutions, a blast could cause life-threatening conditions and severe structural damage.

"Our goal is to protect your homes, no damage to them, and to protect the environment,” Orange County Fire Authority Division Chief Craig Covey said in a social media update Saturday evening.

“Hopefully we can get that done before any failure in the tanks. I am not promising that we're going to fix that but I'm promising you we're doing everything we can to give us a third option that does not involve damaging this community or damaging our environment.”

Firefighters were spraying the outside of the tank with water hoses in an effort to cool the chemicals heating up inside and prevent an explosion.

Lee Zeldin, head of the U.S. Environmental Protection Agency, said Sunday the “most likely scenario” is a “low-volume release,” where officials will be able to “monitor, neutralize, and contain the threat.”

"The Orange County Fire Authority is working to keep the temperature of the tank down. That is very important,” he said on CNN.

He said keeping the temperature under 85 degrees is key.

The evacuation zone was north of Trask Avenue, south
of Ball Road, east of Valley View Street and west of Dale Street, and includes the entire city of Stanton, along with parts of Garden Grove, Anaheim, Westminster and Cypress.

Some Garden Grove residents filed a class-action lawsuit on Saturday against GKN.

Lawyers for residents living in the evacuation zone argued in their federal court lawsuit that regardless of what happens next, property values in the surrounding community are sure to be impacted.

“There is no good outcome here for the people who live nearby,” the lawyers wrote in a statement. “In the best-case scenario, a slow, controlled leak still forces residents out of their homes for an indefinite period, disrupting families, businesses, and daily life. In the worst case, a catastrophic explosion could send a plume and debris across a far wider area, damaging thousands of properties and exposing residents to serious health risks.”

The tank overheated on Thursday and began venting vapors into the air at the aerospace plastics facility in Garden Grove, authorities said. Exposure to methyl methacrylate can cause serious respiratory problems and even render someone unconscious. It can also cause neurological problems and irritate the skin, eyes and throat.

The chemical has “a very strong fruity odor,” Orange County Health Officer Regina Chinsio-Kwong said in a social media update Saturday afternoon.

Newsom declared a state of emergency in Orange County, making state resources available to local agencies and letting state-owned properties and fairgrounds be used for shelters if necessary. Newsom said in a post on X that he had asked President Donald Trump to issue an emergency declaration to bolster federal support for local and state officials.

No injuries had been reported as of Monday morning.

Officials said the valves on the tank are broken or “gummed up,” which prevented crews from removing the chemical or relieving the pressure on the tank, according to Covey.

The Orange County District Attorney’s Office has established an anonymous tipline and online reporting form to gather information about the situation.

“This is an incredibly volatile situation with extraordinary efforts being made by first responders to prevent a potentially catastrophic disaster,” District Attorney Todd Spitzer said in a news release.

Anyone with information related to the circumstances leading up to the incident is asked to call 714-347-8714, fill out an anonymous online form at ocdistrictattorney.gov or email tipster@ocdistrictattorney.gov.

GKN Aerospace, a leading global supplier of vehicle and aircraft components, posted the following statement on its website Saturday:

“There is a serious and evolving situation regarding a thermal issue in a chemical storage tank at our Garden Grove site in California. The situation remains ongoing and we are fully focused on working with emergency services, specialized hazardous material teams and the relevant authorities to ensure the safety of the local community, our employees and everyone else involved. We sincerely apologize for the significant disruption to the many local residents and businesses who have had to be evacuated. We are working tirelessly with all relevant experts to resolve this situation as safely as possible and in a timely manner and are deeply grateful for the continued skill and dedication of the Orange County emergency services.''

On Sunday, the company released another statement saying it was monitoring the “condition of the affected material” and “working around the clock to mitigate the risk of a leak.”

The company has previously agreed to pay state regulators more than $900,000 to settle violations involving recordkeeping, permitting issues and nitrogen oxide emissions, according to a report on the South Coast Air Quality Management District website.

The Associated Press and City News Service contributed to this story.