What to know about California chemical tank set to explode or leak

Tens of thousands of Southern California residents have been evacuated after officials warned a leaking chemical tank holding a "highly flammable" substance at an aerospace facility would inevitably fail and potentially explode. The tank at GKN Aerospace is estimated to contain 7,000 gallons of methyl methacrylate, a "highly volatile" substance used in the production of plastics, according to Orange County Fire Authority Chief Craig Covey. It is not clear when the tank will fail, Covey said. …