The criminal charges against dozens of firefighters who ransacked Montreal City Hall in 2014 have been dropped.

The Crown agreed to withdraw the charges as part of a plea deal that saw the firefighters paying more than $71,000 in fines, including $500 each to a group that helps victims of crime.

The firefighters admitted in writing that they went beyond the limits of acceptable behaviour when they protested changes to their pension plan and how much they were required to pay.

In a statement sent to media on Thursday, the firefighter's union admitted that the actions of its members were inappropriate.

On August 18, 2014, dozens of firefighters stormed into a council meeting and terrorized councillors, chased Mayor Denis Coderre into his office, and made a tremendous mess.

Police stood by and watched, even as firefighters started a bonfire outside the building.

The city fired six firefighters for the role in the violent protest, and another 57 were suspended without pay for anywhere from one week to six months.

As part of the Crown's agreement, the firefighters who trashed City Hall will not have criminal records.

Meanwhile the City of Montreal has worked out a deal with the firefighters about its pension plan restructuring.

As part of the agreement, those six firefighters who were fired will be rehired 15 days after the Executive Committee approves the contract -- their punishment will be effectively become several years of unpaid suspensions.

The disciplinary actions against the dozens of others involved will remain in place.

Under the new contract the City of Montreal will pay 55 per cent of the amount needed to make up the deficit in the pension fund, while firefighters will pay the other 45 per cent.

As of June 2017, firefighters will contribute 2.8 per cent more for their pensions, followed by an additional increase of 2.2 per cent starting Jan. 1, 2018, meaning that as of that point, the employer and employees will contribute equal shares for the retirement fund.