Chemical tank in Garden Grove at 92 degrees Tuesday a.m. as crews work to lower temperature

Fire officials said Tuesday morning, May 26, that the temperature of an overheated chemical container at a Garden Grove aerospace plant remained stable overnight, at 92 degrees as firefighters removed a ground house that had been spraying water over the tank since Friday, authorities said.

“The goal is to see that temperature go down on the tank,” Fire Capt. Brian Yau said. “We removed one of the cooling measures. We want to see the temperatures without that water application.”

The tank, at GKN Aerospace in the 12100 block of Western Avenue, was still being hit with water from a facility system, he said.

Classes resume, businesses reopen as large chunk of evacuation zone is cleared in Garden Grove hazmat threat

Roughly 16,000 residents remain evacuated after the Orange County Fire Authority reduced the evacuation zone Monday, citing that the risk of a BLEVE – boiling liquid expanding vapor explosion – had been averted, officials said. Officials said a crack on the tank, discovered Sunday, was releasing pressure.

Evacuation orders remain in place for residents with a zone bordered by Orangewood Avenue to the north, Dale Street to the east, Knott Street to the west and Garden Grove Boulevard to the south, officials said. A timeline for when residents could re-enter their homes in that area was not known.

Overnight, fire crews also removed material from one of the other two unaffected tanks and transferred it to the third tank because that one has a neutralizing agent, Yau said.

OCFA Interim Chief TJ McGovern said Monday that when firefighters first arrived to GKN Aerospace on Thursday, they were told by a project manager that there was nothing they could do and that a tank filled with 7,000 gallons of methyl methacrylate, a flammable, toxic and highly volatile chemical, was going to fail, either spilling and sending chemicals pouring into a parking lot, or exploding and sending a plume of chemicals into the wind.

McGovern said that was “unacceptable” and that the authority “had to come up with options, solutions. That’s what we do.”

GKN Aerospace, based in the United Kingdom, has 32 manufacturing sites in 12 countries and 16,000 employees, according to its website. The company supplies airframe and engine structures and landing gear, among other aerospace products.

Methyl methacrylate – also known as MMA – is a highly toxic substance that can “impact the respiratory system, cause skin irritation and eye irritation,” Craig Covey, incident commander for OCFA, has said.

It is used as an ingredient in heat-resistant coatings in the aerospace industry and had a long history as an ingredient in products used in nail salons, but it was banned at salons in California since at least 2015.