50,000 Garden Grove residents wait as tank cools

A damaged chemical tank at GKN Aerospace Transparency Systems in Southern California forced evacuations for about 50,000 residents in Garden Grove after methyl methacrylate began venting. Fire crews are working overnight to cool the tank and officials say moni

By late Sunday, officials still hadn’t been able to tell 50,000 residents in Garden Grove, California, that the danger was truly over.

The city—about 40 miles (60 kilometers) south of downtown Los Angeles and home to roughly 170. 000 people—has been under evacuation orders as crews respond to a damaged chemical tank at the aerospace company site. The tank overheated Thursday and began venting vapors. pushing local and state officials into an urgent effort to prevent a worst-case explosion.

Fire crews planned to send in a team for “an all-night mission” to check whether pressure has been relieved. which would reduce the risk of a catastrophic explosion. Orange County Fire Authority interim chief TJ McGovern said in a video posted late Sunday on the agency’s X account. “We are not there yet,” McGovern said, urging residents to stay out of the evacuation zone while operations continued overnight.

In a later update on X, the Orange County Fire Authority said there was one known crack on the tank, disputing reports circulating online of multiple cracks. Officials also said there was no active leak and that continuous atmospheric monitoring confirmed no chemicals were escaping from the tank.

Firefighters have been repeatedly spraying the tank with water to cool the chemical inside. The material is methyl methacrylate, used to make plastic parts. According to Democratic state Sen. Tom Umberg, the tank’s interior reached 100 degrees (37.7 Celsius) Sunday—up 10 degrees Fahrenheit (5.5 Celsius) from Saturday.

Orange County Fire officials said a crack discovered in the tank over the weekend may have helped relieve pressure, reducing the risk of a catastrophic explosion.

At the center of the emergency is a question that residents cannot answer for themselves: whether the cooling is working fast enough to stop pressure from building.

The tank at GKN Aerospace Transparency Systems—an aerospace supplier that makes parts for commercial and military aircraft—holds between 6,000 and 7,000 gallons (22,700 to 26,500 liters) of methyl methacrylate.

Gov. Gavin Newsom declared a state of emergency Saturday and said he asked President Donald Trump to issue an emergency declaration to bolster federal support for local and state officials.

Environmental officials also moved quickly to monitor the area. Monitoring tests found air pollution around the evacuation zone was within normal limits, and specialized equipment was being used to ensure gas was not released, state and federal environmental officials said Saturday.

Drones have been monitoring temperatures at 10-minute intervals to watch for any spikes. Containment barriers have been set up to prevent the chemical from getting into storm drains or reaching creeks or the nearby ocean in the event of a spill. Orange County Fire Authority division chief Craig Covey said on social media.

The chemistry matters here, and officials are walking a narrow line between cooling and risk. As the interior temperature rises. methyl methacrylate converts from a liquid to a gas and increases pressure. Purdue University engineering professor Andrew Whelton said. He added that a crack could mean product or pressure is being released. reducing the chance of explosion—describing it with a comparison: “Think of a soda can. If you leave it in a hot car it can explode,” Whelton said. “But if you put a hole in the can, the product is released and the can itself doesn’t explode.”.

Firefighters are unlikely to consider making a hole in the tank, Whelton said, fearing a spark that might ignite volatile and flammable gas. He described an explosion that could spread the chemical over a broad area and send shrapnel flying as the worst-case scenario.

For residents, the waiting has been physical. Aerial photos showed streets empty Sunday while evacuation shelters remained open. At a high school in neighboring La Palma, people slept in cars or on mats and sleeping bags on the asphalt.

Garden Grove sits next to Anaheim, home to Disneyland’s two theme parks, which were not under evacuation orders. Park officials said they were monitoring the situation.

Health experts say the threat isn’t limited to a potential blast. Exposure to methyl methacrylate can cause serious respiratory problems. neurological problems. and irritation to the skin. eyes. and throat. according to fact sheets about the chemical. Whelton said methyl methacrylate is easy to smell, and people may notice it over a large area without being harmed.

The emergency response also carries an air-monitoring challenge. Whelton said that if an explosion occurs. it will be crucial to conduct detailed air monitoring specifically for methyl methacrylate—not just generic tests for volatile organic compounds—citing the 2023 train derailment in East Palestine. Ohio. That incident released more than 115. 000 gallons (435. 000 liters) of vinyl chloride after officials blew open five tank cars and burned the chemical.

Officials have said no injuries have been reported.

While crews focus on temperature, pressure, and monitoring, some residents are already pursuing accountability. Some Garden Grove residents filed a class-action federal lawsuit Saturday against GKN Aerospace Transparency Systems. which operates the facility where the tank is located. Lawyers for the residents argued that regardless of what happens. property values in the surrounding community are sure to be impacted.

GKN Aerospace did not comment on the lawsuit, but it has apologized to residents and businesses forced to evacuate. It said Sunday it was “working around the clock to mitigate the risk of a leak.”

The company also agreed in 2025 to pay state regulators more than $900,000 to settle violations involving recordkeeping, permitting issues, and nitrogen oxide emissions, according to a report on the South Coast Air Quality Management District website.

There was one thing officials seemed to agree on: even with cracks identified and monitoring in place, the decision that matters—whether the tank can be stabilized—has not yet been delivered.

Garden Grove GKN Aerospace Transparency Systems methyl methacrylate chemical tank evacuation Orange County Fire Authority TJ McGovern Gavin Newsom class-action lawsuit air monitoring Purdue University Andrew Whelton