WSCC investigates ammonia leak that led to evacuation of downtown Hay River

The Workers' Safety and Compensation Commission is investigating what led to an ammonia gas leak in Hay River, N.W.T., on Monday.

A pipe containing ammonia was accidentally cut by a reciprocating saw during demolition work at the town's Don Stewart Arena and several downtown blocks were evacuated for 11 hours.

Ammonia — a colourless compound of nitrogen and hydrogen that can be harmful or even fatal if inhaled in large doses — is used in ice rinks as a refrigerant. The rink has not had ice on it for months.

A spokeswoman for the WSCC says employers are required to remove hazardous chemicals before demolition begins.

"We are currently working to determine cause and ensure compliance with our legislation," Kim Walker said in an email.

'They cut a pipe they shouldn't have cut'

Hay River Fire Chief Ross Potter says the fire department's own investigation of the accident is complete.

"They cut a pipe they shouldn't have cut," he says. "Under normal circumstances the system would have been emptied long before anybody cut any pipes, but one of the workers made an error."

Demolition at the recreation centre began at the beginning of July.

Potter says he has spoken with the contractor, Clark Builders, to remind them of the town's expectations for the work site.

Dave Brothers of Clark Builders says the worker was in an isolated area where he had been instructed not to be. 

Brothers says the chemicals have now been cleared from the site.