Washington mill tank flagged as unsafe months before fatal blast
A chemical tank at a Washington paper mill was flagged as unfit for service months before it failed, killing 11 workers in May.
Federal investigators have revealed that a chemical storage tank at a Washington state paper mill was flagged as unsafe nearly a year before it catastrophically failed, killing 11 workers in one of the deadliest U.S. industrial accidents in recent memory.
The U.S. Chemical Safety Board (CSB), in an update released Friday, said an inspection contractor had determined the tank at the Nippon Dynawave Packaging facility in Longview was "not fit for continued service" in July 2025. The tank ultimately ruptured on May 26, 2026, releasing roughly 900,000 gallons of a highly caustic processing liquid known as white liquor.
The contractor, Applied Technical Services LLC, identified "significant thinning" in the tank's lower sections during an external inspection, finding it below the calculated minimum safe wall thickness. Follow-up inspections in October 2025 and February 2026 reiterated that large portions of the tank remained dangerously thin.
Despite the warnings, the CSB said the company did not perform the recommended internal inspections or shell repairs, nor did it take the tank out of service or reduce its operating capacity.
The failure occurred shortly after 7 a.m., minutes after workers had begun their shifts. The tank had been filling with white liquor after a connected digester vessel was taken offline for repairs, and it reached near-full capacity just before the rupture.
The resulting flood of caustic liquid destroyed part of a building, crushed vehicles, and poured into lower floors where morning meetings were underway. Eight workers in an electrical maintenance shop and one in the courtyard were killed. Two more died in a mechanical maintenance shop, and several others, including a firefighter, were injured.
The CSB also noted that the company's emergency response was hampered by a lack of communication. A medical team member, unaware the liquid was white liquor, waded into the pool to attempt a rescue and suffered serious chemical burns.
Separately, the Washington Department of Ecology has issued 35 environmental violation notices to the company this week. The CSB's investigation remains ongoing, with a final report expected later.