Workers at the Mississauga Transportation and Works Department say they saw fellow employees physically abused and degraded numerous times over the years at the instigation of their supervisor. (CBC)

Two supervisors in Mississauga's Transportation and Works Department have been suspended without pay over the hazing of employees and will have to submit written apologies to residents, staff and council.

Speaking after a closed-door session of council Wednesday afternoon, Mississauga Mayor Hazel McCallion wouldn't identify the supervisors or give details on the length of their suspension.

McCallion said she hopes incidents such as those made public last week in which Works Department employees were shown to be bound with duct tape and pelted with water balloons by other employees don't happen again but that there are no guarantees they won't.

In their investigation of employees' complaints about hazing and humiliation of co-workers at the urging of supervisors, Peel Regional Police interviewed 24 people.

They said Wednesday that they have decided there are no grounds for criminal charges as eye witnesses confirmed that the employees involved in the hazing incidents consented to the activity.

Police Chief Mike Metcalf met with the mayor and councillors Wednesday afternoon.

Coun. Carolyn Parrish walked out of the meeting, saying it was inappropriate for council and police to discuss the matter while police are still investigating.

Police decided to review the workers' complaints after one employee's cellphone video was made public last week. It shows two employees being pelted with water balloons as they lie on a table at a Works Department sign depot. The men are bound together with duct tape.

Employee Alex Juani, who is currently on stress leave, said he showed police the video last March. He and other city workers said some employees had been beaten and abused by other workers for about five years.

They said workers were often subjected to birthday spankings and that one employee was bound with duct tape, put on the back of a truck and sent through a car wash.

The city was first approached about the hazings in November 2009 and had a private investigator look into the complaints. It said it took appropriate disciplinary action following that investigation and made changes to its workplace harassment policies but no employees were suspended at that time.