A serious incident occurred at a chemical storage tank in Garden Grove, California, where overheating caused by a malfunctioning valve raised alarms about a potential disaster. This event poses risks of toxic plume exposure for residents and potential damage to nearby structures.

Since Thursday, Southern California officials have united with state and federal agencies to prevent what could be one of the gravest chemical accidents in California’s history. A state of emergency was declared, leading to the evacuation of thousands of residents in this city southeast of Los Angeles, with an uncertain timeline for their return.

By Monday evening, the threat of a boiling liquid expanding vapor explosion (BLEVE) was successfully averted, according to Orange County fire officials.

Here’s an essential overview of the situation.

What is Methyl Methacrylate?

The incident centers around a storage tank at the GKN Aerospace Facility, holding approximately 7,000 gallons of methyl methacrylate.

Methyl methacrylate is a toxic substance utilized in the production of resins and plastics like plexiglass.

Exposure to this chemical may cause skin and eye irritation, along with symptoms such as coughing, dizziness, headaches, and respiratory issues.

What Were the Risks?

Last week, the Orange County Fire Department reported the tank was heating up and expanding.

This scenario presented two dire outcomes: either the tank develops a crack leading to chemical leakage, or it ruptures and explodes, posing risks to nearby methyl methacrylate tanks.

Fire Chief Craig Covey, the incident commander, highlighted the severity of the situation: “What we were told indicated a potential leaking or exploding tank.”

Fire officials resolved the BLEVE risk by Monday morning, a condition where the temperature of a flammable liquid in the tank increases to the point of catastrophic explosion.

Andrew Welton, a Purdue University engineering professor, likened the risk to leaving a soda can in a hot car—high pressure leads to explosive potential.

On Monday, officials confirmed that a crack allowed pressure to escape, although no chemicals leaked, and the internal temperature was decreasing. Firefighters used sprinklers and hoses to cool the tank.

Initially, around 60,000 residents were evacuated due to their safety concerns; by Monday evening, this was reduced to approximately 16,000.

Why Did the Tank Overheat?

Authorities reported a faulty valve in the tank’s cooling system initiated a dangerous sequence of events.

“The overheating was due to a valve freeze within the recirculating cooling system, which was supposed to maintain a target temperature of 50 degrees,” Chief Covey explained.

This malfunction led to a significant heating of the tank contents.

Mayor Stephanie Klopfenstein assured residents of a transparent investigation into the incident on Monday night.

Has the Risk Been Eliminated?

The temperature peaked at at least 100 degrees Fahrenheit, while the boiling point of methyl methacrylate is around 212 degrees. By Monday, temperatures decreased to 93 degrees.

Welton noted the cooling trend is promising; it indicates no ongoing heat generation within the tank.

Despite this, risks of a minor explosion or chemical spill remain due to uncertainties regarding the chemical’s state within the tank. Some specialists suggest solidification might be occurring.

“If solidification occurs, the threat diminishes significantly,” Welton mentioned.

By Monday, cooler temperatures and solidified materials signaled good news for emergency responders.

Orange County Interim Fire Chief TJ McGovern remarked that while the threat of a major explosion has subsided, additional precautions are still necessary.

He emphasized the need to address potential fire hazards, minor explosions, or chemical spills.

Do You Have Environmental Concerns?

Chris Myers from the Environmental Protection Agency stated that extensive air monitoring revealed no hazardous exceedances during the incident.

According to Welton, the crack in the tank could theoretically allow for some vapor or gas escape.

In response to the incident, President Trump approved a presidential emergency declaration to allocate more resources, including personnel and equipment from FEMA. Governor Gavin Newsom also declared a state of emergency in Orange County.

FEMA has teams assisting in state emergency operations, and air monitoring has been established at 20 locations around the affected area.

The Orange County District Attorney’s Office has initiated an investigation, while two local residents have filed a class-action lawsuit against GKN Aerospace, the facility’s owner.

In an official comment, a GKN Aerospace spokesperson referred to their online statement, conveying their collaboration with fire officials to stabilize the tank.

“We safely removed the tank’s external insulation to assist in cooling its contents,” they stated. “We regret the disruption this incident has caused and are focused on ensuring a safe resolution so residents can return home.”

Covey reported that a nearby tank was neutralized with a chemical compound, although a similar approach was not viable for the threatening tank due to a malfunctioning valve.

Judith Enck, former EPA official, remarked on the necessity of regulatory inspections: “When was the last inspection of this tank, and what were the findings?”

Experts like Welton suggest investigating the maintenance frequency and possible clogging within the tank.

“We hope this incident remains a major alert rather than leading to uncontrolled chemical release or structural damage,” he concluded. “This remains a situation to monitor closely.”