Updated

Updated · The New York Times · Aug 28

Federal Report Says Washington Paper Plant Used Tank Known Unsafe Before 11 Deaths

Updated

Updated · The New York Times · Aug 28

Federal Report Says Washington Paper Plant Used Tank Known Unsafe Before 11 Deaths

Q: What catastrophic pressure failure finally triggered the implosion of the deteriorating chemical tank, spilling 900,000 gallons of toxic liquor?

Investigators have not yet determined the exact triggering failure, but the leading scenario described by experts is a sudden vacuum-pressure collapse inside the tank. The available evidence suggests G Tank likely imploded inward rather than exploded outward. That points to a catastrophic loss of internal pressure — potentially because white liquor was being drawn out or conditions inside the tank changed without enough air or vapor entering to replace the volume, or because a vent or pressure-relief device malfunctioned or became blocked. Experts compared that mechanism to a plastic bottle collapsing when liquid is sucked out without air backfilling it. What is firmly established by the Chemical Safety Board is that the tank had severe wall thinning and had been deemed “not fit for continued service” months earlier. On the day of the disaster, a process upset stopped white liquor from leaving for the digestor while more liquor continued flowing into the tank, pushing it to about 90% full shortly before failure. Investigators are still examining whether that operating upset, combined with venting or pressure-control problems and the already weakened shell, produced the final implosion. So the catastrophic pressure failure most plausibly was an internal vacuum or venting failure, but federal investigators have not yet issued a final cause.

3 articles · Updated · The New York Times · Aug 28

A federal preliminary report found the tank that imploded at Nippon Dynawave Packaging’s Washington paper plant in May, killing 11 people, had been identified as at risk of failure nearly a year earlier.
July 2025 inspections found significant wall thinning in G Tank, which held a caustic sodium hydroxide and sodium sulfide mixture, and follow-up checks in October 2025 and February 2026 again led inspectors to urge an internal inspection and repairs.
The Chemical Safety Board said the company neither inspected the tank internally nor repaired its shell before the May 2026 disaster.
Nippon Dynawave instead kept using G Tank without reducing the amount of liquid stored or how often it was used, sharpening scrutiny of the plant’s safety decisions.