Note: this is an AI summary of press reporting on this story
The U.S. Chemical Safety and Hazard Investigation Board (CSB) has released a preliminary 11-page investigation update on August 28, 2026, revealing that the catastrophic chemical tank collapse at the Nippon Dynawave Packaging Company mill in Longview, Washington, followed 10 months of unheeded structural warnings. The May 26, 2026 disaster resulted in 11 worker fatalities and three severe injuries when a carbon steel storage tank failed, releasing roughly 900,000 gallons of scalding, highly corrosive white liquor.
Key Preliminary Findings by the CSB
- Deemed Unfit for Service: In July 2025, a third-party contractor (Applied Technical Services) conducted ultrasonic testing and explicitly informed Nippon Dynawave that the tank “was not fit for continued service” and faced a “high likelihood / consequence of failure” unless immediately repaired
- Severe Wall Thinning: The inspection revealed that the tank’s shell had thinned significantly due to corrosion, with some lower sections deteriorated to nearly two-thirds of their original designed thickness—falling well below safe structural minimums
- Repeatedly Ignored Warnings: Follow-up assessments in October 2025 and February 2026 confirmed continuing deterioration. Despite instructions to take the tank offline for internal inspection or reduce its operational volume, the mill kept the tank in normal, active operation until it burst
- Nippon Dynawave’s Pushback: The company issued a statement expressing “deep disappointment” with the CSB’s initial update, claiming the federal document omitted critical context and actions taken by management leading up to the disaster
- CSB Chairperson Steve Owens expressed deep concern regarding why the tank was neither repaired nor promptly removed from service given such definitive hazard data. The CSB’s final comprehensive report is expected to take up to two years to complete
