California avoids 'worst-case scenario' in Garden Grove: chemical tank explosion ruled out as evacuation zone shrinks from 50,000 to 16,000 people

The chemical crisis that erupted Thursday in Garden Grove, in southern California, took an encouraging turn Monday. Orange County authorities confirmed that they managed to avoid the most feared scenario - a catastrophic explosion of the malfunctioning chemical tank—and began to reduce the evacuation perimeter that came to encompass 50,000 people.

About 16,000 people still remain under evacuation orders, Garden Grove Police Chief Amir El-Farra said during a news conference Monday night. The figure represents a considerable drop from the height of the emergency, when responders believed there were only two possible outcomes: a detonation or a major toxic spill.

"The most catastrophic and worst-case scenario was mitigated and resolved," stated Orange County Fire Authority (OCFA) interim chief TJ McGovern. Even so, authorities warned that the situation is not fully under control, as the risk did not disappear and, if an explosion or leak were to occur now, its scope would be much smaller than originally projected.

The element that turned the tide was the drop in temperature inside the tank, which allowed the stored substance to begin to solidify, although technicians could not specify by how much. "We are happy to report that the threat of a BLEVE [Boiling Liquid Expanding Vapor Explosion] is now off the table," McGovern said.

The 34,000-gallon (about 128,700-liter) tank contains methyl methacrylate, an industrial compound used in the manufacture of plastics. According to the Environmental Protection Agency (EPA), it is primarily a respiratory irritant. The tank is at a facility of GKN Aerospace, a manufacturer of engines and landing gear for commercial and military aircraft, about 30 miles south of Los Angeles.

On the judicial front, Orange County District Attorney Todd Spitzer opened a criminal investigation and ordered the company not to destroy or alter any records. The goal is to shed light on how an aircraft component manufacturer could allow a failure of this severity. "This is an incredibly volatile situation with extraordinary efforts being made by first responders to prevent a potentially catastrophic disaster," he said.

GKN avoided referring directly to the investigation, but referred to its Monday statement,in which it said it is working "around the clock" with OCFA, the EPA and federal, state and local agencies to mitigate the risk of leakage. The emergency, which began Thursday, prompted Gov. Gavin Newsom to declare a state of emergency in Orange County.