A chemical tank at a Washington state paper mill was flagged as unsafe nearly a year before it exploded and killed 11 workers, according to a federal report released Friday.
The U.S. Chemical Safety Board found that an inspection contractor told Nippon Dynawave Packaging Company in July 2025 that the tank was not fit for continued service. The company made none of the recommended repairs before the tank failed on May 26, 2026, at its facility in Longview. The explosion expelled enough caustic liquid to blow out building walls, injuring several workers and one firefighter in addition to the 11 deaths.
According to ABC News, the July 2025 inspection found significant thinning below the minimum safe thickness in the lower regions of the tank. An excerpt from the inspection report listed the recommendations as "Priority 1: Not fit for continued service unless corrected," with a "high likelihood/consequence of failure (or) critical code/standard deficiency."
The same inspection excerpt stated: "Owner should plan to have an internal inspection performed in order to determine the extent of the required repairs. It's likely that the entire shell course should be replaced."
The contractor, Applied Technical Services LLC, returned in October 2025 and again in February 2026. Both times, inspectors found that large portions of the tank wall remained thinner than the calculated minimum safe thickness. The board noted that the company also did not remove the tank from operation or reduce it to a lower service level during that period.
The tank failure released roughly 900,000 gallons of white liquor, a liquid used to break down wood in paper production that is capable of causing severe chemical burns.
The catastrophic failure came just minutes after employees began arriving around 7 a.m. Shortly before 2 a.m. that morning, a piece of equipment called a digestor was taken offline for repairs, which caused white liquor to stop flowing out of the tank. More liquid continued flowing in, pushing the tank toward full capacity around 6 a.m.
The Chemical Safety Board said it is still determining the official cause of the failure. An email seeking comment was sent to Nippon Dynawave, and the company had not responded publicly as of the report's release.
The board's update is part of an ongoing federal investigation into one of the deadliest U.S. workplace disasters in recent decades.
