1676811622 Dismantling the Champlain Bridge Protecting the St Lawrence at All

Dismantling the Champlain Bridge: Protecting the St. Lawrence at All Costs

Constructed in the late 1950s, the bridge has been severely tested by Quebec winters and required strengthening over the years before its access was permanently closed on June 28, 2019.

The 3.4-kilometer structure that connected Montreal to Brossard via the Île des Soeurs consisted of 200,000 tons of concrete and 25,000 tons of steel. Materials that the workers salvage instead of letting them sink into the depths of the St. Lawrence River.

Unlike other demolished bridges, the Champlain Bridge was not intended to be destroyed with explosives. The engineers are betting on dismantling the structure and avoiding any maneuver that could cause it to collapse into the river.

Dismantling the Champlain Bridge Protecting the St Lawrence at All

Time lapse video of the descent of the main span of the old Champlain Bridge.

Antoine Audoynaud, project leader of the New Horizon St-Laurent (NHSL) consortium, which brings together the engineering firms responsible for the work, prefers not to talk about deconstruction [de] Demolition.

The teams coordinating the bridge’s demolition also wanted to prevent the operations from disrupting the river’s delicate ecosystem, which is inhabited by fish and birds, including species with precarious status. In particular, it had to be ensured that the bridge parts did not get into the water, since the grease, paint and lead they contained could have endangered these population groups.

The Champlain Bridge in numbers

  • 3.4 kilometers long
  • 200,000 tons of concrete
  • 25,000 tons of steel
  • 42 spans removed
  • 48 stacks and 45 deconstructed foundations
  • 92 disassembled modular trusses

Deconstruct without disturbing wildlife

In order to carry out this delicate operation, each tonne moved was calculated in advance. And each step is thought out so as not to disturb the species that inhabit the Saint Lawrence River.

The St. Lawrence River has been very disturbed in the past, explains Philippe Larouche, environmental project manager at Les Ponts Jacques Cartier and Champlain Incorporated (PJCCI), the federal Crown Corporation that oversees mining.

“It is important that we change the way we work, that we take the most innovative measures and that we protect the environment. »

— A quote from Philippe Larouche, Environmental Project Manager at PJCCI

The decommissioning work, which started in August 2020, required the installation of a huge temporary pier in the Île des Soeurs sector. Almost 120,000 tons of rock were dumped into the river to allow teams to dismantle the bridge deck on dry land rather than in the water.

The stones of the pier were chosen to prevent erosion or suspended matter from sinking into the river, Philippe Larouche points out.

Dominique Forget and Hélène Morin’s report airs Sundays at 6:30 p.m. on ICI Radio-Canada Télé’s Découverte program.

Since the jetty was on the migratory route of several species of fish – such as bass and sea sturgeon, which are likely to be designated endangered species – corridors were built to allow water to flow through the works.

The oceanographer Stéphane Lorrain, who supervised the installation of these passages, recalls that fish usually go upstream to find substrates in the spring. Some species can ascend as far as the Lachine Rapids, he notes.

Underwater cameras and electrodes made it possible to track the movements of the fish. According to Stéphane Lorrain, a sign of the success of the installations is that the upstream runs reached hundreds of fish per day in May 2021.

A woman and a man, dressed in bibs and hard hats, look at the sky through binoculars.

Catherine Julien and Timothée Ostiguy, environmental consultants, observe cliff swallows that have built their nest in the structure of the bridge.

Photo: Radio Canada / Discovery

Other teams have instead been keeping an eye on rock martins, whose populations have been declining across the country.

These birds, which tend to build their nests in the cliff faces, had taken up residence in the Champlain Bridge structure. Although nets have been installed under the bridge decks to discourage swallows from dwelling there, some nests have still been found on the edges of the bridge.

But dismantling the structure while the chicks were there was out of the question for fear of disrupting the breeding season. Every discovery of an active nest led to an interruption in operations, forcing the teams to review the phases of the work, says Philippe Larouche.

Thousands of tons of recovered materials

Only once on the floating barges or on the banks of the river could various elements of the bridge be deconstructed or destroyed in order to recycle the materials.

The crews first tackled the trellis that had been installed to reinforce the concrete beams damaged by the de-icing salts. In the summer of 2021, workers on floating platforms gently lowered these huge 50-ton pieces.

Brought to the quays, these grilles were dismantled before going to the foundries. They are either processed into steel beams or into vehicle parts, Antoine Audoynaud cites as an example.

Cranes are busy demolishing the structure on a closed road.

Route 132, a vital link for Montreal mobility, was closed to traffic while four spans of bridge were demolished.

Photo: Radio Canada / Discovery

Of the forty approach spans that made up the bridge, 30 were deconstructed from the water between the Île des Soeurs jetty and the St. Lawrence Seaway.

This difficult task was accomplished thanks to an imposing cargo catamaran. Its area, which covers the equivalent of two NHL playing fields, and its elevator system, which can reach nine stories and lift up to 4,800 tons, have earned it the nickname “giant of the river”.

With the cargo catamaran approaching 5,500 tons once the span was removed, engineers limited the platform’s movements on the river and opted to wreck its cargo using cranes directly on the water.

A span of the bridge rests on a structure that rises several meters aboard a floating barge.

The impressive cargo catamaran that made it possible to dismantle the spans of the bridge was christened “giant of the river”.

Photo: Radio Canada / Discovery

The concrete was then transported to the wharf in smaller barges before being sent to a recycling center where it was crushed for reuse in sidewalks.

Unhooked in mid-winter 2022, the main span was brought to shore before being dismantled in the spring. While some parts were intended for research, the vast majority were recycled.

We have recycled all steel materials within a 150 km radius, explains Philippe Larouche. This is a measure to prevent the steel from being containerized and sent abroad for recycling and then sold to us.

However, other elements of the structure were located at the bottom of the river, such as the concrete foundations poured every 50 meters to support the bridge piers (piers). Surrounded by barges, steel tubs and a rubber membrane, the piles were demolished in a sealed area where the concrete was reclaimed.

Cranes work in a pool of water on a floating platform.

A watertight zone was created so that the cranes could demolish the 10 meter wide foundations at the bottom of the river.

Photo: Radio Canada / Discovery

The soles were also destroyed directly in the water using sonar and GPS in an area sealed off by steel walls.

Into the large holes left by the foundations, the teams dumped large rocks to restore the fish’s natural habitat.

From this major operation, which spanned more than three years, only a few pillars will remain, testifying to the Champlain Bridge, which was once one of the busiest in Canada.

PJCCI estimates that the decommissioning work will be completed in the winter of 2024.

The Disappearance of the Champlain Bridge in Data

June 2019 : Closure of the bridge to traffic

Aug 2020 : Start of dismantling in the Île des Soeurs sector

January 2022 : Dismantling of the main span

April 2022 : Demolition of cantilevered steel structures at Brossard

May 2022 : Destruction of piles and foundations at the bottom of the river

November 2022 : Destruction of spans over Route 132

January 2024 : Estimated end of work

Based on an account by Dominique Forget and Hélène Morin of Découverte