Investigation into gas release finds Woodland mill negligent

A preliminary report from a federal agency's investigation has found that the Woodland Pulp mill was negligent in not having sufficient safety measures in place to prevent and alert workers about the buildup of a highly toxic gas that caused the deaths of two employees at the mill this past winter. In a July 14 update on its investigation, the U.S. Chemical Safety and Hazard Investigation Board (CSB) states that Woodland Pulp was aware of the risks caused by hydrogen sulfide gas forming in the acid sewer pipe but did not have the necessary systems in place to monitor or mitigate the risk. Also, the bleach plant's scrubber fan that removes the gas had been turned off as part of the mill's shutdown operations.

The release of the gas on January 27 resulted in the deaths of a 20‑year‑old University of Maine co‑op chemical engineering student, Kasie Malcolm, and a 26‑year‑old chemical engineer, Allen Hornberger, who had only recently joined the company. Ten additional employees were also exposed to the toxic gas. In addition to the fatalities and injuries, the property damage from the incident, which includes loss of use, exceeded $16 million.

CSB Chairperson Steve Owens says, "Although our investigation is still ongoing, it already is clear that this terrible tragedy should never have happened. The two young employees who died were not provided with personal hydrogen sulfide monitors that would have alerted them to the presence of the toxic gas, and there were no hydrogen sulfide detectors installed in the building where the release occurred. The company also did not keep track of who was in the building and where they were during this horrible event. As a result, the two young employees were not found until hours after the release ended, leaving them exposed to the highly toxic gas without assistance."

Elizabeth Kayatta, a wrongful death attorney with Berman & Simmons who represents Kasie Malcolm's mother and Allen Hornberger's parents, comments, "The Chemical Safety Board's update is clear: neither Kasie nor Allen had anything to do with causing the toxic gas release. These two boys were casualties of a corporate culture that prioritized profits over people. Many questions still remain about the shocking disregard for safety that developed at Woodland Pulp while under the ownership of International Grand Investment Corporation."

Attorney Kayatta says the CSB's investigation points to longstanding issues at the mill, including damage to the acid injection system, a lack of building ventilation at the kraft mill and multiple holes in gas collection pipes and vents that had gone unrepaired for years since IGIC purchased the mill in 2010.

Report outlines incident

At the pulp mill, wood chips are chemically processed into pulp for papermaking in an area called the bleach plant, which is located in the kraft mill. From the bleach plant, an acid sewer pipe over 1,000‑feet‑long collects liquid waste from multiple areas of the mill before flowing by gravity to the facility's wastewater treatment plant. A portion of the pipe flows upward, causing liquid to accumulate in the acid sewer at that point.

The discharges collected in the acid sewer pipe often contain alkaline process fluids that can contain sulfur compounds. Woodland Pulp sometimes adds sulfuric acid to the acid sewer pipe to control the pH of the discharge. However, when sulfuric acid combines with high‑pH process fluids that also contain sulfur, the substances react to produce highly toxic hydrogen sulfide gas. Typically, if a small amount of hydrogen sulfide gas is produced within the acid sewer pipe, the toxic gas is removed by a scrubber in the bleach plant before it can be released to the atmosphere.

The CSB report describes that on January 27 operations were in the process of being shut down due to an increase in the price of natural gas, which caused significantly higher operating expenses. As part of the shutdown, operators started draining equipment between 12:30 and 2:30 a.m. When process fluids drained into the process sewer pipe connecting the bleach plant to the wastewater treatment plant, automated settings triggered the release of sulfuric acid around 4 a.m., which reacted with fluids in the pipe to form toxic hydrogen sulfide gas. Between 10:30 a.m. and noon, drain valves were opened on the first floor of the kraft building and the bleach plant's scrubber fan was shut down.

Toxic accumulations of hydrogen sulfide gas then flowed out from the piping through holes and process openings in equipment into the interior of the multi‑story kraft mill. The area lacked any stationary hydrogen sulfide detectors or alarms, and workers had not been provided portable monitors to wear. Ten workers on the first floor were exposed to the gas. Some experienced symptoms such as burning eyes and throat, and at least one lost consciousness.

When Woodland Pulp employees discovered the high hydrogen sulfide gas levels in the building, they began an emergency response by closing the manual emergency shut‑off valve at the sulfuric acid supply tank and opening a manual water flush valve to the acid sewer pipe, which flushed the accumulated chemicals past the upward transition. The remaining toxic hydrogen sulfide gas in the building dissipated by 3 p.m., roughly three hours after the bleach plant's scrubber fan had been turned off and the release began.

It was not until hours later, approximately 6:15 p.m., that Malcolm and Hornberger were found collapsed on the kraft mill's second floor near damaged pipes that hydrogen sulfide gas had flowed out of. They had been working on a project unrelated to the shutdown process that was happening on the first floor below them. The report says they were likely exposed to over 500 parts per million of hydrogen sulfide gas, with the gas considered immediately dangerous to life at a concentration of 100 ppm. Malcolm died the next day, and Hornberger passed away on February 16 after he was taken off life support.

The CSB's investigation found that there was no system for accounting for personnel present in the kraft mill building during the shutdown and there was no building ventilation. Also, there were no stationary hydrogen sulfide detectors in the bleach plant, and the company neither provided nor required employees to wear personal hydrogen sulfide monitors.

CSB board member Sylvia Johnson says, "Our investigation update notes that Woodland Pulp was aware of the hazards associated with hydrogen sulfide gas forming in the acid sewer piping, but despite this knowledge the company did not have adequate systems in place to monitor or mitigate the hazards. This safety gap likely led to the severity of this tragic incident."

The investigations into the incident by CSB and by the Occupational Safety and Health Administration, the Environmental Protection Agency and the Maine Department of Environmental Protection are ongoing. In upcoming weeks, more information is expected to be made available for public release.