The mill was evacuated and several nearby roads were closed after a series of explosions sent a cloud of toxic gas into the air threatening public health and safety.
The mill's investigation revealed the toxic emission was caused by a lack of water necessary to absorb chlorine dioxide. The chlorine dioxide became unstable, causing pressure to build and burst the plastic piping. In addition, a compressor left in automatic mode allowed additional releases. Chlorine dioxide is used by the mill to bleach pulp.
"The community is extremely lucky that nobody was injured. This was a very dangerous situation that resolved itself quickly, thanks to good weather conditions and a quick response from the mill's workers," said Carol Kraege of the Department of Ecology (Ecology).
"Our priority was to make sure that our employees and the community were safe and fortunately they were," said Randy Cox, the mill's environmental health and safety manager. "We've now taken further precautions to prevent this from happening again."
The mill extracts cellulose from wood chips to manufacture chemical pulp, which is used to make products ranging from film to toothbrush handles.
Weyerhaeuser has 15 days to apply to Ecology for relief from the penalty and 30 days to appeal it to the state Pollution Control Hearings Board.