White Liquor Tank Collapse at Longview Paper Mill

Location: Nippon Dynawave Packaging facility, Longview, Washington, United States

Incident Summary

On May 26, 2026, at approximately 7:15 am Pacific Daylight Time, a catastrophic structural failure occurred at the Nippon Dynawave Packaging mill. An industrial storage tank with a 900,000 gallon capacity, which was holding approximately 600,000 gallons of white liquor, collapsed inward.

The physical consequences of the incident include:

Casualties: The incident resulted in 11 fatalities. Nine employees died at the scene, and two succumbed to their injuries at regional medical facilities. Eight additional individuals, including seven plant workers and one responding firefighter, sustained injuries ranging from chemical burns to respiratory inhalation trauma.

Structural Damage: The structural failure of the tank and the subsequent release of fluid damaged nearby administrative structures and an operational employee break room. The timing of the failure coincided with a facility shift change, which placed more personnel within the immediate impact zone.

Environmental Release: The chemical solution spilled into a facility drainage ditch system and entered the adjacent Columbia River. Environmental monitoring confirmed elevated pH levels in the ditch network, though municipal officials reported that the city drinking water supply remained unaffected.

Facility and Process Description

The incident occurred at the Nippon Dynawave Packaging Co. facility, an integrated pulp, paper, and liquid packaging board plant that has been operating since 1953. The site employs approximately 1,000 workers and manufactures bleached paperboard and market pulp used to produce items such as beverage cartons, paper cups, plates, and tissues.

The substance involved was white liquor, an aqueous solution primarily composed of sodium hydroxide and sodium sulfide. In the kraft pulping process, this alkaline chemical stream is combined with wood chips under elevated temperature and pressure to dissolve lignin, which isolates the cellulose fibers required for papermaking.

Speculation on Potential Contributing Factors

Based on initial structural observations and external expert commentary, the following scenarios represent technical possibilities:

Ventilation Blockage: The inward buckled geometry of the tank shell indicates a vacuum collapse. If the atmospheric vent or vacuum relief valve on top of the tank became obstructed by chemical scaling, crystalline deposits, or mechanical binding, a rapid liquid draw-off or a sudden drop in ambient temperature would generate an internal pressure significantly lower than external atmospheric pressure.

Structural Fatigue: Long term exposure to highly corrosive alkaline solutions can result in localized wall thinning or stress corrosion cracking. A mechanically compromised tank shell would possess a reduced critical buckling pressure, making it vulnerable to collapse under minor internal vacuum conditions.

Primary Information Sources

The Associated Press (AP): "Chemical tank implosion in Washington state kills 1 and leaves 9 missing" and "How a chemical tank disaster struck at the heart of a Washington state mill town" (Published May 2026).

Oregon Public Broadcasting (OPB): "'Something dramatically wrong': Questions but few answers after Longview mill tragedy" (Published May 30, 2026).

CBS News: "Bodies of all 9 missing workers recovered after chemical tank implosion at Washington state paper mill" (Published May 30, 2026).