Garden Grove chemical threat: 40,000 evacuated as overheated tank faces explosion or leak

GARDEN GROVE, Calif. – An overheated chemical storage tank at an Orange County aerospace manufacturing plant has forced the evacuation of approximately 40,000 residents, with emergency officials warning that the compromised vessel will either rupture or explode.

What we know:

The incident began at around 3:30 p.m. Thursday at GKN Aerospace, located at 12122 Western Ave. in Garden Grove. 

That’s where a 34,000-gallon storage tank containing methyl methacrylate (MMA)—a toxic, highly flammable liquid chemical used to manufacture acrylic plastics—became severely overheated.

Orange County Fire Authority (OCFA) Division Chief Craig Covey stated that a faulty valve on the tank has blocked emergency crews from accessing, off-loading, or introducing a neutralizing stabilizer into the chemical material. 

PREVIOUS COVERAGE: Hazardous chemical leak forces second round of evacuations in Garden Grove, Stanton

Experts from across the state and country have been consulted, but local authorities report the tank can no longer be mitigated or secured, leaving only two final outcomes.

“There are literally two options left remaining. One, the tank fails and spills a total of about 6,000 to 7,000 gallons of very bad chemicals into the parking lot in that area, or two, the tank goes into a thermal runaway and blows up, affecting the tanks that are around them that have fuel or the chemicals in them as well,” said Chief Covey.

First responders have constructed “containment barriers” around the site to block potential liquid runoff from entering storm drains, river channels, or the ocean. 

Officials noted that a controlled spill is the “best case scenario, believe it or not” compared to an explosion.

Air quality is being continuously monitored by emergency personnel and drone teams tracking the tank’s temperature. All air readings remain within healthy limits, and there is no active gas leak or toxic plume. No injuries have been reported.

Local perspective:

The current mandatory evacuation zone forms a one-mile buffer around the facility, encompassing parts of Garden Grove, Westminster, Stanton, and Anaheim. 

The boundaries cover the following areas:

• North of: Trask Avenue
• South of: Ball Road
• East of: Valley View Street
• West of: Dale Street

>> TAP OR CLICK HERE TO SEE A MAP OF THE EVACUATION ZONE <<

What we don’t know:

It’s unclear what initial failure caused the chemical inside the GKN Aerospace tank to overheat. 

While authorities have asserted that the tank is going to fail, the exact timing of a potential chemical rupture or thermal explosion is unknown.

Timeline:

Thursday, 3:30 p.m.: OCFA crews and Garden Grove police respond to GKN Aerospace after the overheated tank begins venting vapors and triggering automated safety sprinklers. Initial evacuations are ordered.

Thursday Night: Crews believe they are making progress cooling the tank with continuous water streams; evacuation orders are temporarily lifted.

Friday, 4:00 a.m.: Chief Covey receives an emergency call indicating the tank’s condition has severely worsened.

Friday Morning: Evacuation orders are re-instituted and subsequently expanded to a one-mile radius due to changing and volatile conditions.

Friday Midday: Unified command announces that the tank cannot be secured mechanically, leaving a leak or explosion as the only remaining outcomes.

Saturday Morning: Evacuation orders remain strictly in place for 40,000 residents as monitoring continues.

What they’re saying:

Garden Grove Mayor Stephanie Klopfenstein strongly urged residents to comply with emergency directives.

“We understand it is frightening people who are worried about their homes, their businesses, their pets and loved ones. But this is a serious situation and now is not the time to wait.”

Orange County Health Officer Dr. Regina Chinsio-Kwong highlighted the health hazards of the chemical involved, noting that MMA is “very toxic” and can impact humans severely based on animal studies.

“It can cause significant irritation in the lungs, the nasal passages, and it can also cause nausea, it can also cause dizziness. If it can have that type of effect in mice it can have that same effect in humans.”

Representative Derek Tran (D-Westminster) issued a statement confirming federal involvement: “My office is in close contact with local police, fire, and emergency response officials as they work to contain the hazardous materials, assess air quality, and ensure residents and first responders are safe. I am in contact with federal disaster relief officials, including FEMA and the EPA, to urge them to provide any available federal assistance for Garden Grove.”

What’s next:

Emergency teams will continue utilizing drones to track internal tank temperatures while awaiting structural failure or a potential chemical breakthrough.

Localized closures, cancellations, and service disruptions will persist until the site is declared safe:

Public Infrastructure & Closures

Road Closures

• Beach Boulevard is completely closed from Garden Grove Boulevard to Orangewood Avenue
• State Route 22 (Garden Grove Freeway) off-ramps at Beach Boulevard, Knott Avenue, and Valley View Street are closed

School Closures

The Garden Grove Unified School District has canceled all classes until further notice at:

• Barker Elementary
• Bryant
• Carver
• Enders Elementary
• Garden Park
• Lawrence Elementary
• Wakeham Elementary
• Patton Elementary
• Bell Intermediate
• Alamitos Intermediate
• Pacifica High School
• Rancho Alamitos High School
• Skylark Preschool
• The Maintenance and Operations Facility
• The Lampson Bus Yard

Community Events & Elections

• Voting: One vote center (Garden Grove Sports and Recreation Center) and three ballot drop boxes inside the evacuation zone are closed. The affected drop boxes are located at Stanton Branch Library, Korean Martyrs Catholic Center, and Chapman Sports Park.
• Festivals & Food Banks: The Garden Grove Strawberry Festival at the Village Green remains open but has canceled its scheduled and community breakfast. The Giving Farm food bank operation was forced to cancel its Friday distribution.
• Major Attractions: Nearby tourist destinations, including Disneyland and Knott’s Berry Farm, remain fully open but are actively monitoring the situation.

What you can do:

Impacted residents must immediately vacate the exclusion zone and seek regional shelter.

Available Evacuation Centers

• Garden Grove: Garden Grove Sports and Recreation Center, 13641 Deodara Drive
• Cypress: 5700 Orange Ave.
• Fountain Valley: 16801 Euclid St.
• Anaheim: Savanna High School, 301 N. Gilbert St.
• Huntington Beach: Oceanview High School, 17071 Gothard St.

Voting Alternatives

Evacuated voters who do not have their vote-by-mail ballot can request a replacement at any of the remaining 38 Orange County vote centers opening Saturday. Completed ballots can also be deposited at any of the 125 unaffected drop boxes. Registered voters can find mapping resources at ocvote.gov/voting.

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