GKN Aerospace Plant in Garden Grove Faces Overheating Chemical Tank

Emergency crews continued efforts Sunday to stabilize a storage tank at a GKN Aerospace plant in Garden Grove after the container began overheating Thursday. The tank holds roughly 7,000 gallons of methyl methacrylate, a flammable chemical used in plastics manufacturing.

m. Monday, the point at which the chemical may generate heat faster than crews can remove it. The South Coast Air Quality Management District said the condition is known as thermal runaway.

Aerospace reached a $910,000 settlement with the South Coast Air Quality Management District in January 2025 over permit violations, missing emissions records, and nitrogen oxide issues at the same Garden Grove facility. Inspectors first documented violations during a November 2020 inspection.

The agency issued a notice of violation in April 2021 and continued working with the company on documentation and compliance in subsequent years.

County fire officials said a pressure-release valve malfunction on Friday prevented crews from stopping the reaction. Evacuation orders were expanded to Garden Grove, Anaheim, Buena Park, Cypress, Stanton, and Westminster. California Gov. Gavin Newsom declared a state of emergency on Saturday to provide additional state resources and shelter locations.

Garden Grove Mayor Stephanie Klopfenstein urged remaining residents to leave, stating the situation is very dangerous. Hazmat teams are monitoring temperatures and applying cooling measures. Officials said crews may need to withdraw if conditions continue to deteriorate.