Washington chemical tank was called unfit for service before deadly failure, investigators find

An inspection contractor found a chemical tank at a Washington state paper mill "not fit for continued service" 10 months before it failed in May, killing 11 in one of the deadliest U.S. workplace disasters in recent decades, according to a federal report released Friday.

The U.S. Chemical Safety Board's update about the May 26 failure in Longview, which expelled enough caustic liquid to blow out building walls, is part of an ongoing investigation. The federal agency said it is still determining the cause of the failure.

The board found that the contractor provided Nippon Dynawave Packaging Company with recommendations for internal inspections and shell repairs, but the company did none between a July 2025 inspection and the May 2026 failure.

"Because the investigation remains ongoing, we will not comment on individual findings or documents at this time," an emailed statement from Nippon spokesperson Sam Jefferies said Friday. "Our focus remains on supporting affected families and employees and taking the necessary steps toward fully reopening the Longview facility."

Jefferies said the company will continue to cooperate fully with the board.

The Association of Western Pulp and Paper Workers released a statement on Friday saying the board's findings were "deeply troubling."

"The update raises urgent questions about how technical findings and recommendations concerning the tank were communicated, evaluated and incorporated into decisions about its continued operation," the statement said. "The families and workforce deserve a complete accounting of that process."

In July 2025, the contractor found "significant thinning" below the minimum safe thickness in the lower regions of the tank after an external inspection, according to the board's report. The minimum safe thickness is a threshold that measures a tank's ability to contain the pressure of the liquid and support the tank's weight, the report said.