WINNIPEG -- The Winnipeg Police Association is filing a grievance over proposed changes to the police pension plan.

Moe Sabourin, president of the WPA, says he’s already delivered documents to Mayor Brian Bowman.

Bowman confirms he received the documents which he says he immediately handed over to the city’s legal team.

An arbitrator could rule on the matter.

Sabourin says the city can’t make unilateral changes to the pension plan without negotiating.

The city has received a legal opinion on the issue.

The proposal, passed Tuesday morning by the mayor’s executive policy committee, would see overtime removed as a pensionable earning and officer contributions increased while the city’s share would decrease.

Mayor Brian Bowman says the changes will make the plan sustainable, allowing the city to allocate some savings to policing services.

“It’s simply an unsustainable pension,” said Bowman.

The report estimates $12 million in savings a year.

The changes require final approval from city council later this month.