Peter Kennedy, 50, was killed in October 2009, and three others were injured, when a boiler blew in a steam plant that helps heat the parliamentary precinct and other downtown buildings.
Public Works and Government Services Canada — the sprawling bureaucracy that serves as the federal government's property manager — initially faced eight charges under the Labour Code for the accident.
It pleaded guilty to failure to provide the necessary health and safety training for the operation of a boiler; failure to adequately train supervisors and managers in health and safety issues; and failure to develop a program for the prevention of workplace hazards.
The maximum penalty under each count is a fine of $100,000. A sentencing hearing will come in the new year.
"Our thoughts and prayers go out to the family of the deceased," Michael Bolkenius, a spokesman for Public Works Minister Rona Ambrose, said in a release.
"The government of Canada takes the issue of employee's health and safety very seriously. We are committed to ensuring safe workplaces for all public servants and for persons accessing federal premises."
But NDP public works critic Linda Duncan called it "absolutely reprehensible" that public service supervisors in the Public Works Department had no safety training, noting that the private sector is expected to meet labour codes.
"If any department in the government of Canada should be setting an example in the training and safety and the protection of its workers, surely it should be Public Works and Government Services," said Duncan.
The department issued a release saying that immediately following the 2009 accident, Public Works "began actively implementing a number of additional health and safety measures for our employees and the plants they operate."
Those measures include enhanced training, a review of occupational safety programs and hiring a third party to review operations and emergency evacuation plans at the Cliff Plant in Ottawa where the deadly blast occurred.
The cause of the explosion remains unknown, according to an agreed statement of facts in the Ontario Court of Justice.
Note to readers: This is a corrected story. An earlier version identified Linda Duncan as labour critic, not public works critic.