MONTREAL -- The dismantling of the old Champlain Bridge began in earnest Monday, with the first of 30 concrete spans removed.

A complex undertaking, the entire effort is slated to cost about $400 million.

Most of the work will be carried out on floating platforms, away from residential areas. The platforms reduce the amount of rubble landing in the river, and allow much of the bridge material to be recycled.

The trademark green metal section of the bridge over the St. Lawrence Seaway is going to be dismantled during the winter months so ship traffic isn't disrupted.

The dismantling process started in August 2020. Workers created two corridors to allow fish to migrate safely as part of the project, which is slated to be completed in January 2024.

Watch the bridge dismantling begin in the video above.