NOTE: I normally remove company names, as I am not about name shaming, but this company has earned its shame!
The U.S. Chemical Safety and Hazard Investigation Board (CSB) today released an update on its investigation into the deadly May 26, 2026, catastrophic failure of a 1.2-million-gallon atmospheric storage tank at the Nippon Dynawave Packaging Company, LLC (NDP) pulp and paper mill in Longview, Washington. The tank (identified as G Tank) released approximately 900,000 gallons of extremely hot, highly caustic white liquor, fatally injuring eleven (11) NDP employees and seriously injuring three others.
The CSB’s investigation found that an inspection of the exterior shell of G Tank conducted in July 2025 — approximately 10 months before the fatal incident — identified that significant portions of the tank’s carbon-steel shell had thinned below the calculated minimum safe thickness. The inspection contractor’s report recommended that NDP internally inspect and repair the identified thinned areas of G Tank’s shell. The inspection report also stated that G Tank was “[n]ot fit for continued service” unless it was repaired and that there was a “[h]igh likelihood/consequence of failure”. Despite the inspection’s findings, G Tank remained in service until it catastrophically failed on May 26, 2026.
NDP conducted additional external inspections of G Tank in October 2025 and February 2026. Both inspections also determined that substantial portions of G Tank’s shell remained thinner than the calculated minimum safe thickness. Even after these additional inspections, NDP still did not internally inspect or repair the tank shell, remove it from service, or reduce its operating conditions before it failed.
On the day of the incident, May 26, 2026, a process upset required NDP to stop sending white liquor from G Tank to the digestor at the mill where it would have been used to produce pulp from wood chips. However, even though no white liquor was leaving G Tank, white liquor continued to enter the tank from the recausticizing process at the mill, causing the tank level to rise to approximately 90 percent full by 6:22 a.m.
As shown in recently released surveillance footage, at approximately 7:09 a.m., G Tank catastrophically failed, rapidly releasing approximately 900,000 gallons of the scalding hot (200°F) highly corrosive liquid, flooding the surrounding courtyard and nearby buildings where employees were gathered for morning meetings. Eleven NDP employees were fatally injured, and three were seriously injured by the release. Five additional NDP employees and one firefighter sustained injuries but did not require inpatient hospitalization.
NOTE: I hate to say it, yet I get to as I called it back on May 30th that the visual evidence available at the time pointed to just a wall failure, most likely a weld seam caused by SCC and that there was NO evidence of a vacuum event, as most everyone was reporting. I had no idea of the tank’s inspection history, but as it turns out, this was a serious failure in management/risk decision-making. My hope is this results in WILLFUL citations from LNI (WA-OSHA). SAFTENG members can read my article explaining my approach to investigating the visual evidence available at the time and how I came to my initial conclusion that this was a simple wall failure.