A crack formed in an overheated tank holding 6,000 to 7,000 gallons of methyl methacrylate at GKN Aerospace Transparency Systems in Garden Grove, California, over Memorial Day weekend. The incident led to evacuation orders affecting 50,000 people initially, with 16,000 remaining in place on Tuesday. A separate tank implosion at a Washington state pulp mill injured at least 10 workers the same week.