Specialists investigating a potentially explosive chemical tank at a GKN Aerospace facility in Southern California have discovered what may be a pressure-relieving crack in the container.
TJ McGovern, interim fire chief of the Orange County Fire Authority, announced the development in a video message posted on social media on Saturday night.
McGovern said a team of specialists found “a potential crack in the tank, which could potentially be relieving some of the pressure in there,” describing the discovery as “positive intel.”
The tank at the Garden Grove facility contains methyl methacrylate, a highly toxic and flammable chemical used in plastics and manufacturing, holding up to 7,000 gallons.
Officials have warned since Friday that the tank could rupture or explode, endangering other tanks at the GKN Aerospace site, which is a division of British aerospace supplier Melrose Industries (LON: MRO).
The incident began on Thursday after the chemical started to overheat at the facility, which produces aircraft windshields and specialty aerospace plastics among other products.
Efforts to neutralise the reaction failed due to damage to valves on the tank, fire officials said, prompting evacuation orders covering tens of thousands of residents in the Garden Grove area.
Garden Grove is a suburb located roughly 30 miles south of Los Angeles, and the evacuation orders remain in place while authorities continue to assess the situation.
Authorities are still working to confirm whether the crack has actually relieved pressure inside the tank, with the Orange County Fire Authority spokesperson telling Reuters that lowering pressure could help avert an explosion.
GKN said in a statement: “We continue to monitor the condition of the affected material and are working round the clock to mitigate the risk of a leak.”
Although officials are currently focused on measuring pressure levels, the fire authority spokesperson said the crack could eventually allow authorities to drain the chemicals gradually from the container.
California Governor Gavin Newsom on Sunday requested that President Donald Trump issue a federal emergency declaration to support response operations, having already declared a state of emergency for Orange County on Saturday.
EPA Administrator Lee Zeldin told CNN’s State of the Union programme on Sunday that local officials were working to stabilise the tank by keeping its internal temperature below 85 degrees Fahrenheit.
Zeldin said: “I’m being told this morning that the most likely scenario is one of a low-volume release, where the local authorities are going to be able to monitor, neutralize and contain the threat.”
At one point on Saturday, the tank’s internal temperature reached as high as 90 degrees Fahrenheit, according to the fire authority.
Health officials expressed concern that prolonged exposure to vapour from the chemical could cause severe respiratory problems, though air monitors in Garden Grove detected no chemicals or pollutants on Sunday, the EPA confirmed.
Sensors located around the tank itself had not detected any chemical leaks in the air, the fire authority spokesperson added.
Public records from federal and California agencies show that GKN has a pattern of regulatory violations at the Garden Grove facility, including a settlement of nearly $910,000 reached in late 2024.
The settlement, with the South Coast Air Quality Management District, resolved allegations of multiple rule violations, according to documents provided by the regulator to Reuters.
Crews were preparing for a possible spill by identifying ways to dike, dam, and divert liquid into a holding area at the commercial site, preventing it from reaching storm drains, river channels, or the ocean.