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BAILEYVILLE, Maine – Federal investigators from the U.S. Chemical Safety and Hazard Investigation Board (CSB) have detailed a series of safety failures that led to a deadly hydrogen sulfide gas release at the Woodland Pulp Mill on January 27, 2026. The incident unfolded during an overnight emergency shutdown of the mill’s Bleach Plant, a unit where wood chips are chemically processed into pulp for papermaking. Mill management ordered the shutdown to reduce operating expenses after a spike in natural gas prices, and operators began draining chemical equipment between 12:30 a.m. and 2:30 a.m. As they did so, high-pH alkaline process fluids containing sulfur compounds were routed into a 1,000-foot-long acid sewer pipe that collects liquid waste from several parts of the mill and carries it by gravity toward the facility’s wastewater treatment plant. Investigators reported that a section of this sewer line, designed with an upward transition, allowed the waste mixture to pool and accumulate inside the pipe rather than flow freely. Within this confined area, conditions enabled the formation and release of highly toxic hydrogen sulfide gas, which then exposed workers nearby. The CSB identified the victims as 20-year-old co-op chemical engineering student Kasie Malcolm, who was completing a spring-semester internship with the company, and 26-year-old chemical engineer Allen Hornberger, who had recently joined the mill. Both died from toxic exposure. Ten other employees suffered non-fatal injuries, including burning sensations in their eyes and throats, severe headaches, and respiratory distress after contact with the gas, according to the board’s preliminary update.

Prepared by Emily Rhodes and reviewed by editorial team.