WATCH: More than 1,400 Maple Leaf Foods workers questioning their futures

The planned construction of a sprawling poultry processing plant in London has more than 1,400 workers in three other Ontario communities worried about their futures.

Maple Leaf Foods will break ground this spring on a 640,000 sq ft facility that the company boasts will be one of the most technologically advanced in the world.

It is expected to open in the spring of 2021 with 1,450 full and part time positions.

Maple Leaf Foods Inc.

At the same time, Maple Leaf is preparing to move nearly the same number of positions out of Toronto, Brampton and St. Marys by closing plants in those communities and consolidating their work in the new build. The St. Marys facility is slated to shut down by late 2021 with Toronto and Brampton going dark by the end of 2022.

Together, the United Food and Commercial Workers (UFCW) says the three plants employ 1,490 people: 681 in Toronto, 485 in St. Marys and 324 in Brampton.

"Those jobs are going to be leaving those...communities," says Tim Deelstra with UFCW. "We have concerns about that and what that's going to mean for our members there and for those communities."

Maple Leaf reasons that those locations are old with limited opportunity for growth and modernization, something that Deelstra approaches with some scepticism.

While Maple Leaf has vowed to work with communities and governments to find new uses for the plants when they close and to help workers transition, Deelstra says those conversations have not begun.

Toronto mayor John Tory says he will be looking for assurances from the company that people at the city's poultry plant will be given the opportunity to work at the London facility or elsewhere under the Maple Leaf umbrella.

The London build is expected to cost $660 million with the governments of Ontario and Canada chipping in $34.5 million and $20 million respectively.

"Thanks for putting that money in but what are you going to do now for the workers who are going to be impacted by this move," Deelstra asks.

Maple Leaf says construction of the new London facility will add 300 jobs.