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LONGVIEW, Wash. - A new report reveals that the Longview Nippon Dynawave mill, the site of a chemical implosion which killed 11 workers in May, was under several unrelated investigations by the Washington State Department of Labor & Industries.
According to a news release from L&I, the Nippon Dynawave mill in Longview, Washington was under investigation for safety complaints.
Workers from the agency conducted two inspections of the mill just weeks before the deadly chemical implosion.
Longview mill chemical implosion
On May 26, 2026, a chemical tank containing "white liquor" — a highly corrosive substance used in paper production — violently collapsed, spilling hundreds of thousands of gallons on the ground and billowing huge clouds of caustic, white smoke into the air. Eleven workers died in the incident, and several others were injured by chemical burns or by inhalation.
Many of the bodies could not be recovered for several days, as the site had to be cleared of hazardous chemicals.
The exact cause of the chemical tank failure has not yet been identified. State and federal agencies are expected to release a report about their findings later this year.
A photo of the ruptured tank of white liquor that imploded at the Nippon Dynawave Packaging facility in Longview on May 26, 2026. (via Cowlitz County News) (Cowlitz County News)
WA investigated Longview mill before implosion
L&I revealed they had received a complaint in early March, more than a month before the deadly implosion.
The agency found that Nippon Dynawave "did not document their safety plans or keep required records relating to an ammonia tank used to treat wastewater at the facility."
This is an issue unrelated to the white liquor tank, and suggests mounting safety concerns before the incident on May 26.
According to L&I, a worker reported a broken valve handle on an aqua ammonia clarifier tank used to treat the mill's wastewater. The worker reported the valve's handle was detached and could not be closed.
By the time state inspectors arrived, the handle had already been partially repaired, but managers could not provide documentation of previous safety inspections, and had no formal inspection and maintenance program for the ammonia tank.
Nippon Dynawave was issued a $2,890 citation for failing to develop an inspection program and failing to maintain records.
A second L&I investigation was opened on May 6 after a drain failed and caused a sinkhole at the mill, leading to a worker falling into a four-foot deep hole of hot pulp. State regulators say that investigation is still ongoing.
What's next:
L&I launched a third investigation into the plant shortly after the chemical implosion, which is still ongoing, as well. The agency has a team of investigators working onsite, and they have until Nov. 22, 2026 to issue their findings.
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The Source: Information in this story comes from the Washington State Department of Labor & Industries, as well as previous coverage from FOX 13 Seattle.