Saturday marks four months since an unknown amount of amine was released from the Pine River Gas Plant near Chetwynd, and authorities are still trying to figure out what happened.
The plant, operated by Spectra Energy, released a visible cloud of the noxious gas from a surge tank on Nov. 26 during a start-up procedure.
National Energy Board spokesperson Darin Barter said Wednesday that the investigation in ongoing.
"The NEB investigation of the incident continues and will determine (what happened)," Barter said in an emailed statement to the Alaska Highway News.
He could not provide an estimate on when the final report would be released.
About 55 employees were on site at the time of the incident. None were harmed.
The plant was shut down for several days in the wake of the release, with all staff not related to the investigation barred from entering the property.
At the time of the shutdown, the plant was producing about 150 million cubic feet per day of natural gas, well below its capacity of 560 million cubic feet per day, because of a slowdown in demand.
Spectra Energy's facilities in B.C. have a combined natural gas processing capacity of about 3 billion cubic feet per day.
The amine release happened days after small amounts of hydrogen sulfide (H2S) escaped from the plant.
The Pine River Gas Plant was built in 1979 and had its last major expansion in 1993.