VANCOUVER -- Old equipment that continued to be used seven years after a maintenance contractor recommended replacing it caused an ammonia leak that killed three workers at an ice rink in British Columbia last October, says an organization that oversees the safe operation of refrigeration systems in the province.

Jeff Coleman, director of risk and safety knowledge for Technical Safety BC, said Wednesday the City of Fernie scheduled funding to replace a chilller system in 2013 but it was deferred to 2014 and subsequently deleted from budget plans.

He said ammonia was used to chill liquid at the Fernie Memorial Arena and traces of the gas were found in the liquid as early as the summer of 2017, indicating a leak within the chiller, but the equipment was put back into operation on Oct. 16, the day before the colourless gas leak killed three men.

Coleman said corrosion along a seam in one tube of the chiller had caused tiny hole, allowing pressurized ammonia to seep into the liquid, bursting the pipe and venting large amounts of the deadly gas.

"Once the leaking chiller returned to operation, additional actions and decisions associated with the shutdown configuration were a response to cascading failures beyond the scope of training and situational understanding of those involved," he told a told news conference.

"While the equipment failures originated from a small hole in a chiller tube, Technical Safety BC concluded that the cause of the incident was the decision to operate the leaking chiller," Coleman said.

The release of ammonia triggered an alarm in the arena's mechanical room at about 4 a.m. on Oct. 17.

City of Fernie employees Wayne Hornquist and Lloyd Smith, and refrigeration contractor Jason Podloski of Turner Valley, Alta., died in the room while doing emergency maintenance work.

Coleman said the mechanical room's ventilation system could not have prevented the extremely high levels of ammonia from accumulating as the gas was released so quickly.

Technical Safety BC has made 18 recommendations to prevent similar incidents related to management, maintenance, training and operation, including ventilation related to refrigeration systems.

"As an industry, we must recognize a leaking chiller as a failed component," Coleman said. "We need to implement clear procedures and guidance to safely remove leaking chillers from service once a leak is discovered."

The City of Fernie said it was operating with an approved certification for its cooling system at the time of the leak and its employees were appropriately trained.

It said the report found there was no evidence that anyone was aware of any safety risk associated with the continued operation of the chiller, and the city's maintenance plan was consistent with others in the province.

"As a city we value and are committed to the health and safety of our employees and community members," Mayor Mary Giuliano said in a news release.

"Despite working with an approved certification for our system at the time of the incident, today's report points to opportunities to further improve safety standards for arena refrigeration plants, not only for Fernie but for communities across British Columbia, so no one else will need to experience a similar tragedy."

CIMCO, the refrigeration company Podloski worked for, could not immediately be reached from comment on the report.

Janice Lee, director of safety oversight for Technical Safety BC, said the incident resulted from practices in the industry at the time and her organization took steps during its investigation to immediately improve safety.

That included educating ammonia facilities on the dangers of uncontrolled ammonia release incidents and how to prevent them, she said.

The deaths in Fernie had Technical Safety BC putting more resources into inspecting ice rinks in B.C., she said.

So far, 95 per cent of 185 sites have been inspected, and two were found to have leaking ammonia, and had to be shut down, Lee said, citing the Hollyburn Country Club, which operates a curling rink in West Vancouver, and the Matsqui Recreation Centre un Abbotsford.

Municipal Affairs Minister Selina Robinson, whose ministry is responsible for recreational facilities, said the recommendations for arena owners, maintenance contractors, training providers and local governments will improve safety of ice-rink refrigeration systems so people can feel safe when they attend hockey games, skating practice or other community events.

"Technical Safety BC's recommendations are the result of a thorough investigation under the Safety Standards Act to determine the cause of the tragedy and identify how to help make sure something like this does not happen again," Robinson said in a statement.

Fernie declared a seven-day state of emergency after the deaths, and an evacuation order covering 55 homes near the arena was in effect for nearly a week.

WorkSafeBC and the RCMP are also conducting independent investigations.