A chemical tank in California has cracked. Here’s what to know : NPR

On Sunday, roughly 50,000 residents in Garden Grove, California, remained under evacuation orders as authorities grappled with a potentially explosive threat at a local aerospace manufacturing facility.

Here’s an update on the ongoing situation and potential developments at the plant.

Overnight, the chemical tank appeared to have cracked

Situated in the southeastern part of the GKN Aerospace facility, a tank containing approximately 7,000 gallons of methyl methacrylate—a highly toxic and flammable chemical used in resin and plastic production—showed signs of a crack late Saturday. Firefighters approached the tank to assess the situation, as noted by TJ McGovern, interim county fire chief for the Orange County Fire Authority, in a social media post.

A cracked tank could actually be good news, sort of

The incident began on Thursday, with emergency responders still unclear on the exact cause. The chemicals in the tank had exceeded safe temperatures. Methyl methacrylate, a clear and volatile liquid, releases energy exothermically upon reaction, potentially causing explosive pressure build-up in a confined space.

A similar incident occurred in the UK in October 2009, where a resin manufacturing site explosion involving the chemical caused significant damage. While no fatalities were reported, damage extended to nearby buildings, with windows shattered up to 600 feet away.

The California tank, already showing signs of bulging, is being continuously cooled with water. It is located near two other tanks, one of which has been safely drained and neutralized, while the other remains stable. Incident commander Craig Covey explained on Friday that a crack in the damaged tank might be the best scenario, allowing the chemical to leak slowly instead of causing an explosion.

“In a weird world that’s the best case scenario believe it or not,” Covey remarked. “Because once it comes out it is no longer an explosive hazard.”

There are still many environmental and health hazards

GKN Aerospace stated on Sunday that it is “working around the clock to mitigate the risk of a leak.” The hazards associated with methyl methacrylate include skin and eye irritation, respiratory issues, neurological symptoms like headaches and lethargy, and potential long-term organ damage.

While the environmental impact of a spill remains unclear, it is expected to be negative. To prevent chemical flow into nearby drains and waterways, Covey mentioned that containment barriers have been set up, with firefighters using sand and other materials for this purpose.

For now, residents must remain evacuated

Evacuees check-in at a shelter on May 22 after tens of thousands of people were ordered to leave their homes in Garden Grove, California Friday after a huge chemical tank began leaking, with warnings it might blow up, sending toxic fumes over a heavily populated area.

Blake Fagan/AFP via Getty Images

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Blake Fagan/AFP via Getty Images

“We know that you’re out of your homes, we want to get you back, but we cannot do that until it’s deemed safe,” Orange County Fire Chief McGovern stated in a video message on Sunday. Residents are being evacuated to guard against a potential explosion and the harmful fumes it could release. Given the unpredictability of the fume’s direction, a wide area around the plant is being evacuated.

So far, no fumes have been detected by firefighters or the Environmental Protection Agency, which has established monitoring stations around the facility.

McGovern expressed hope that the new crack in the tank “could potentially be relieving some of the pressure in there,” offering a step toward resolving the crisis. “We’re not there yet, but this was a step in the right direction,” he said. “And there could be a lot more coming shortly.”