Washington AG Launches Criminal Investigation into Nippon Dynawave Paper Mill Disaster
The Washington State Attorney General’s Office has launched an investigation into whether criminal activity contributed to the catastrophic white liquor tank implosion at Nippon Dynawave Packaging (NDP) in Longview on May 26, which claimed the lives of 11 workers and injured eight others.
The investigation, announced on July 1, is being carried out in coordination with the Cowlitz County Prosecutor’s Office, which granted the Attorney General’s Office concurrent authority to assist due to the scale and complexity of the incident. Officials emphasized that the investigation is in its early stages and that no allegations or findings of wrongdoing have been made. If evidence of criminal conduct is identified, appropriate legal action will be pursued.
Meanwhile, the Washington State Department of Labor & Industries (L&I) has expanded its safety oversight by launching inspections at two additional kraft pulp and paper mills: Smurfit Westrock’s Longview facility and Port Townsend Paper Co. The inspections, announced on July 2, are separate from the agency’s ongoing investigation into the NDP disaster.
L&I’s investigation into the Longview explosion aims to determine the cause of the incident, identify any workplace safety violations, and recommend corrective actions to prevent similar accidents. The agency has up to 180 days to complete its investigation, with findings expected by November 22. Following the release of the report, the employer will have an opportunity to respond and appeal any violations within the legally prescribed period.
The new inspections at the other mills will focus on compliance with state workplace safety regulations related to storage tanks and hazardous chemical handling. Investigators will review tank maintenance and inspection records, operating and maintenance procedures, incident histories, and environmental reports involving spills or other safety concerns. The inspections are expected to take up to six months to complete.
In addition, L&I has launched a targeted enforcement program covering Washington’s seven non-kraft pulp and paper mills to assess chemical storage and handling practices. The initiative will continue through February 2027 as part of the state’s broader effort to strengthen worker safety across the paper industry.
At the federal level, the U.S. Chemical Safety and Hazard Investigation Board (CSB) continues its investigation into the accident. The agency has identified four primary areas of focus: the mechanisms that led to the tank failure, facility siting, maintenance and mechanical integrity, and applicable facility, corporate, and industry standards. A preliminary update is expected by the end of September, with a final report anticipated next spring.
Production at Nippon Dynawave Packaging remains suspended while parent company Nippon Paper continues to assess the financial impact of the incident.
Emergency response agencies have completed the removal of approximately 12,000 gallons of liquid from the damaged white liquor tank, allowing the unified command overseeing the response to stand down on July 1. However, the Washington Department of Ecology will continue its own review to determine whether the incident violated state or federal environmental regulations governing water quality, air quality, or hazardous waste management. The department also plans to seek reimbursement from the company for state response costs incurred during the emergency.
The NDP disaster has prompted coordinated investigations by local, state, and federal authorities, highlighting a renewed focus on industrial safety and chemical hazard management within Washington’s pulp and paper sector.
