Thousands of residents in Garden Grove, California, received permission to return home Monday after officials said the risk of a catastrophic explosion at a chemical storage tank had been largely contained, though evacuation orders remained in place for about 16,000 people.
The incident at the GKN Aerospace facility involved a 7,000-gallon tank of methyl methacrylate that began overheating Thursday due to a malfunction in its refrigeration system. Orange County fire officials reported a vapor release that prompted an extensive response involving firefighters, federal agencies and company personnel working to prevent a boiling liquid expanding vapor explosion, known as a BLEVE.
Interim Orange County Fire Chief TJ McGovern addressed reporters Monday evening and stated, "The most catastrophic and worst-case scenario was mitigated and resolved." He added that the situation was not fully resolved, noting ongoing concerns about fire, a small explosion risk and potential spills.
Evacuation orders, which initially affected around 60,000 people in the northern Orange County city located about 35 miles southeast of Los Angeles, were scaled back significantly by Monday. Garden Grove Police Chief Amir El-Farra urged remaining residents to comply with the orders, saying, "Please understand that we are doing this for your safety."
Division Chief Craig Covey explained that a valve in the tank's recirculating refrigeration system froze, preventing the chemical from being kept at the required 50 degrees Fahrenheit. Temperatures inside the tank climbed as high as 100 degrees before dropping to 93 degrees by Monday, according to Covey.
Firefighters poured millions of gallons of water onto the tank and activated deluge sprinklers to reduce the temperature and lower fire risks. On Monday, a crack in the tank released pressure without causing a leak, allowing crews to remove insulation and speed up cooling efforts.
A GKN Aerospace spokesperson said in a statement that the company removed insulation from the tank on Sunday and has been working around the clock with federal and state agencies. Covey noted that the company has been cooperative, adding that GKN hired a contractor to assist with the response.
No injuries have been reported from the incident, which began with the vapor release at the facility where the chemical is used to manufacture resins and plastics. Air monitoring conducted with 20,000 instruments across the region showed no exceedances of contaminants, according to Chris Myers, the federal on-scene coordinator for the Environmental Protection Agency.
Officials emphasized that there has been no contamination from either the incident or the response efforts. The remaining evacuation orders for 16,000 residents were set to be reevaluated Tuesday morning.
The facility is located roughly four miles from Disneyland in Anaheim, though no impacts to the theme park or surrounding areas beyond the immediate evacuation zone were reported. Covey previously described a potential BLEVE and spill as possibly one of the worst chemical events in state history.
Residents who were allowed to return were advised to remain cautious as work continued at the site. McGovern stressed that firefighters still needed to address the remaining hazards before declaring the situation fully under control.
Local authorities asked for patience from those affected by the prolonged evacuations, noting the complexity of stabilizing the overheated tank. The response involved coordination between Orange County Fire, the EPA and GKN Aerospace personnel.
Further updates on the evacuation status and any additional measures were expected following Tuesday's assessment by incident commanders.