The OCFA found a possible crack in the tank threatening to explode in Garden Grove

Orange County Fire Authority Chief TJ McGovern posted an update this morning about the chemical tanks that are threatening to explode at GKN Aerospace Transparency in Garden Grove. McGovern said that last night the OCFA emergency team has involved subject matter experts. The team found a potential crack in the 7,000 gallon tank that has been pressurizing. That may be relieving some of the pressure that has been building up in that tank.

Today the OCFA emergency team is vetting and validating the information about the possible crack in the tank. This new development could change the OCFA’s trajection and strategy as they work to prevent the tank from exploding.

After initially lifting orders, the Orange County Fire Authority (OCFA) reissued and widened the boundaries into a roughly one-mile buffer zone to protect residents from a potential catastrophic rupture, toxic plume, or explosion. The expansion grew the evacuation zone to encompass an estimated 50,000 to 79,000 residents.

Updated Evacuation Boundaries

The expanded evacuation zone now spans across portions of six different Orange County cities—Garden Grove, Stanton, Anaheim, Cypress, Buena Park, and Westminster—and is generally defined by these major roads:

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

Note: While the evacuation zone extends slightly south of the 22 Freeway, the highway itself has remained open. Major nearby attractions like Disneyland and Knott’s Berry Farm are outside of the zone and operating normally.

Updated Evacuation Centers

The Orange County District Attorney announced that they are investigating the situation and are looking for tips from the public. Employees at GKN can call the OCDA and their jobs will be protected by the Federal Whistleblower Act.

The South Coast Air Quality Management District also announced that they have a mobile van near the tank site that is taking air measurements. They are reporting that the levels of pollutants are completely normal however that will most certainly change if the 7,000 gallon tank that is currently undergoing a chemical reaction ruptures. If it BLEVEs (a boiling liquid evaporation vapor explosion) it will likely compromise a 15,000 gallon tank next to it. BLEVEs are essentially giant fireballs as the liquid in the tank will instantly vaporize once it is released. The vapor will be many times the volume of the liquid.

The OCFA issued a map showing the potential blast area if the tanks BLEVE. The map identifies three areas. The Severe Damage Blast Zone, which is in the middle of the map, will likely suffer catastrophic damage.

The chemical at risk of exploding at the GKN Aerospace facility in Garden Grove, California is methyl methacrylate (MMA).

Chemical and Situation Details

• Purpose: This volatile and highly flammable liquid monomer is used by the GKN Aerospace Transparencies division to manufacture durable, lightweight, clear acrylic plastics—such as cockpit windows and military aircraft canopies.
• The Hazard: The substance is undergoing an uncontrolled, heat-generating chemical reaction called a thermal runaway reaction. As pressure and temperature continuously build inside a compromised 34,000-gallon industrial tank, it risks a violent structural rupture or catastrophic explosion.
• Emergency Response: First responders have been constantly spraying the tank with water to keep it cool. They are unable to inject neutralizing agents because a critical tank valve is jammed.
• Impact: Due to the imminent explosion and toxic vapor risk, a state of emergency was declared for Orange County, enforcing mandatory evacuation orders for roughly 50,000 residents in the surrounding 9-square-mile zone.

If the tanks BLEVE (Boiling Liquid Expanding Vapor Explosion), anyone in the immediate area must evacuate immediately to at least 2,500 feet (800 meters) in all directions. A BLEVE creates a catastrophic fireball, intense radiant heat, and supersonic flying shrapnel.

1. Evacuate Immediately

• Move at least 2,500 feet away.
• Avoid line-of-sight exposure to the tanks.
• Do not stop to gather personal belongings.

2. Seek Structural Cover

• Put thick concrete or brick structures between you and the blast.
• Stay away from glass windows and doors.
• Drop to the ground if caught outside without cover.

3. Protect Your Lungs

• Close all windows and doors if you are safely outside the evacuation zone.
• Turn off air conditioners and ventilation systems.
• Cover your nose and mouth with a damp cloth.

4. Monitor Official Channels

• Listen to local emergency management announcements.
• Follow specific evacuation routes provided by first responders.
• Do not return to the area until authorities declare it safe.

5. Render Basic First Aid

• Treat thermal burns with cool water immediately.
• Seek medical attention for blast injuries or smoke inhalation.
• Keep airways clear for anyone struggling to breathe.

Be sure to follow the OCFA at https://x.com/OCFireAuthority to keep getting their updates. We will continue to post about this emergency as well.

The Orange County Sheriff is also making an emergency resources website available here.

About the Editor

The Editor of the New Santa Ana blog, Art Pedroza, has worked in safety and risk control for over 30 years. He is a former 40-hour Hazwoper (Hazardous Waste and Emergency Response Operations) instructor with experience in refineries and construction. He has spent over 15 years in risk control in commercial insurance. He is a former member of the Orange County Emergency Medical Services Commission. Pedroza currently teaches for a painting apprenticeship program at Cerritos College and he is a part-time lecturer at CSUF in their School of Public Health.