Following a toxic gas exposure incident in January, which caused the deaths of two workers, the Woodland Pulp mill experienced another accident on March 7. The Jan. 27 exposure to hydrogen sulfide gas occurred when the mill was shutting down operations because of the high price of natural gas. The March 7 leak of hydrogen peroxide occurred while the mill was in the process of restarting operations following the month-long shutdown.
According to Scott Beal, spokesperson for the mill, shortly after 9 a.m. workers noticed a drain valve had become opened, which resulted in the loss of approximately 4,000 gallons of hydrogen peroxide into the mill’s sewer system. Peroxide is a compound used in the kraft mill’s bleaching process, along with chlorine dioxide. Exposure to hydrogen peroxide, which is considered a hazardous substance, can cause skin, lung and eye irritation, or even severe burns and blindness. It also can cause explosions.
Some of the hydrogen peroxide came in contact with bleached pulp, possibly from a prior spill, that was on the ground adjacent to the peroxide tanks, according to Beal. The resulting reaction generated smoke but no open flames. He said that mill employees promptly called the Baileyville Fire Department, and the mill’s hazmat team was toned out to assist the fire department.
“The stock/peroxide reaction event was addressed quickly once the first responders were on site,” Beal said. “Fortunately, no property damage was incurred nor any injuries sustained.”
Once the peroxide tank inventories were reconciled against consumption, an estimate of the volume of hydrogen peroxide lost to the sewer system was then determined. With this information, the mill notified state and federal environmental agencies. Beal said the hydrogen peroxide that was released will be treated in the mill’s extended aeration lagoon system and the system will be monitored closely. “It’s anticipated this event will not have any adverse impact to the receiving waters of the St. Croix,” he states.
Beal said that the cause of the drain valve being open is still being investigated. He noted that there have been a number of issues related to restarting the mill. When the mill was being shut down, some of the equipment froze, and maintenance work needed to be done to repair the equipment. As of March 9 the mill was still working to get fully back on line for sustained production.