Overview
- A storage tank holding methyl methacrylate began overheating last Thursday after a refrigeration valve failed, raising alarms about a possible BLEVE, or boiling liquid expanding vapor explosion.
- Responders found a crack that relieved internal pressure, which allowed crews to strip insulation and apply water more directly and prompted officials to say the worst‑case explosion risk had been averted.
- Authorities reduced the evacuation zone, letting roughly two‑thirds of displaced residents return home while about 16,000 people remain under evacuation and many continue to use temporary shelters.
- The EPA and South Coast Air Quality Management District report no air exceedances so far, but crews continue external cooling, storm‑drain and air monitoring, and officials warn smaller fires, spills or limited explosions are still possible.
- Orange County’s district attorney has opened a criminal investigation with preservation orders and a whistleblower line, and state and federal agencies plan multi‑month inspections and oversight of GKN Aerospace’s records and response.