OTTAWA -- The federal government reached a deal with striking workers on Friday to keep the central heating plants at military bases running after three were taken off-line.

The Union of National Defence Employees is part of the Public Service Alliance of Canada, and its members have been on strike since Wednesday.

National president June Winger said the government failed to consider heating and wastewater plant workers as essential during the strike, leading to a shortage of staff.

"The employer is obligated to determine what the essential services are to maintain the safety for Canadians, and they failed miserably in this regard," she said in an interview.

"I'm gobsmacked."

Winger said central heating plants at bases in Petawawa, Ont., Winnipeg and Halifax were forced to shut down.

There was concern the heating plant at Royal Military College in Kingston, Ont., and the wastewater treatment plant in Winnipeg may also stop running.

Winger said the union and employer agreed back in December on how many staff were needed to perform essential functions, and that the Defence Department "dropped the ball."

"The local managers knew weeks ago, and nothing was said, nothing was proposed until the day we go on strike," she said.

A spokesperson for the Department of National Defence said the Treasury Board and the union signed an agreement Friday afternoon to add more positions to that list.

Winger said around 15 more heating plant workers across the country are now considered essential workers.

"We have agreed to that in the interest of keeping Canadians safe and ensuring that the military remains operationally ready," she said.

Operations restarted late in the day in Petawawa, where the Defence Department said heating and hot water were both disrupted at the garrison.

When the heating plants were shut down, bases lost everything from cooling systems to hot water for kitchens and shower facilities.

Winger said a shortage of staff at the wastewater plant at 17 Wing Winnipeg could have serious environmental impacts.

This report by The Canadian Press was first published April 21, 2023.