40,000 evacuated in California chemical leak as officials warn tank may explode

More than 40,000 people were evacuated in multiple Southern California cities on Friday after officials warned a leaking toxic chemical tank at an Orange County aerospace facility would inevitably fail and potentially explode.  

The industrial tank at the Garden Grove facility is estimated to contain 7,000 gallons of methyl methacrylate, a “highly volatile” and “highly flammable” toxic substance used in the production of plastics, said Orange County Fire Authority Chief Craig Covey.

“This is gonna happen unless some brilliant guy behind me here figures out how we can mitigate this incident,” Covey said at a news conference Friday afternoon. “This thing is gonna fail. We don’t know when.”

Orange County officials expanded evacuation orders on Friday to several cities, including Garden Grove, Cypress, Stanton, Anaheim, Buena Park and Westminster.

OCFA officials said there are three tanks in total, with one of the three compromised in its cooling system. 

“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 and that area,” Covey said. “Or two, the tank goes into a thermal runaway and blows up, affecting the tanks that are around it that have fuel or chemicals in them as well.”

Covey said it was unclear how widespread or dangerous an explosion could be, and said the timeline was unknown.

“We want to prepare for the worst, but expect for things to get better,” he said.

He noted that a team has been assembled to “think outside the box,” with a county hazmat team calling on experts throughout the state and country to help search for solutions to depressurize the affected tank and mitigate exposure. 

“Right now, there is no active gas leak coming off that thing,” Covey said of the tank, noting there was currently nothing harmful in the air. “We have cooled it down enough that the purge valve that is on top of it is no longer purging any kind of product from the liquids there.”

Air quality remains a concern, but Covey said that there is not an active plume, and no air particulates are “compromising anybody.” People are advised to stay indoors. 

Garden Grove Unified School District officials closed 15 campuses on Friday morning and said they would remain closed until further notice as they continued monitoring the situation.

What is methyl methacrylate?

Health experts said that methyl methacrylate — a flammable plastic epoxy that generates its own heat — is a respiratory irritant and potential exposure could lead to lung, skin and eye irritation, nausea and dizziness. The chemical is heavier than air, so its vapor would settle and sink.

Air monitoring is ongoing, and drones are monitoring the temperature of the tank, officials said.  

When did the Garden Grove chemical leak start?

Crews arrived Thursday afternoon at the GKN Aerospace facility in the 12000 block of Western Avenue in Garden Grove after receiving a hazardous materials call just before 3:40 p.m. that day, according to OCFA. 

The chemical in the industrial tank initially stayed at the same temperature, officials said. However, about four hours after firefighters arrived, the temperature rose, causing a relief valve and sprinkler system to activate near the tank.  Firefighters said the sprinkler safety system is designed to cool off the tank if it starts leaking. 

The OCFA said crews initially made progress toward removing the chemical product but determined Friday morning that the “tank that is in the biggest crisis is in fact unable to be secured and mitigated.”

The cause of the leak remains under investigation. No injuries have been reported. 

Safety information 

City of Garden Grove 24-hour call center (714) 741- 5444, or visit: ggcity.org/emergency

Orange County public information hotline (714) 628-7085.   

Evacuation centers

Garden Grove: Garden Grove Sports & Recreation Center, 13641 Deodara Dr. 

Cypress: Cypress Community Center, 5700 Orange Ave.