Samuel De Champlain Bridge - Lapierre Island Project

Table of Contents

• Lapierre Island Project Background and Objectives
• Project Description, Timeline and Characteristics
• Environmental Benefits of the Project
• Mitigation Measures During the Work

Lapierre Island Project Background and Objectives

Large-scale construction projects inevitably impact the environment. Many compensation projects were analyzed by Infrastructure Canada in collaboration with Fisheries and Oceans Canada, Environment and Climate Change Canada, and Public Services and Procurement Canada, to offset the loss of natural environment caused by the construction of the Samuel De Champlain Bridge.

The Lapierre Island project, located in the district of Rivière-des-Prairies–Pointe-aux-Trembles, was selected because it has the greatest ecological potential.

There used to be a marsh on Lapierre Island. However, it was destroyed by recurring deposits of fill materials from Montreal between 1980 and 1983.

Therefore, the project's objective is to recreate Lapierre Island's natural environment so that it can be used by wildlife. The marsh will be recreated, which will enable the restoration of fish spawning, nursing and feeding activities and generate habitats suitable for other species, including birds.

Project Description, Timeline and Characteristics

The marsh restoration project was carried out in two phases:

Phase 1: Marsh preparation work (December 2016 – summer 2017)

• Consolidation of the existing bridge by modifying and adding bracing (support structure);
• Clearing of the work area;
• Excavation and disposal of the fill;
• Implementation of various mitigation measures during the work.

Phase 2: Creation of the marsh and hydrologic connection with the Rivière des Prairies (summer 2017 – spring 2018)

• Excavation and disposal of the fill;
• Creation of channels between the new marsh and the Rivière des Prairies;
• Profiling of the marsh, the floodplain and channels;
• Re-vegetation of the banks and floodplains using indigenous plants adapted to the sector's aquatic conditions;
• Opening of the channels to enable a permanent hydrologic connection between the new marsh and the Rivière des Prairies;
• The implementation of various mitigation measures during the work.

Characteristics of the Marsh:

• The marsh covers 1.5 hectares;
• Excavation was just over 5 metres deep in some areas;
• Excavation of over 60,000 m3 of soil;
• The marsh's maximum depth was between 3.5 and 2.3 metres, depending on the level of Rivière des Prairies;
• The development was designed to allow for a large river opening during periods of high water that was then be restricted to three permanent openings during periods of low water levels;
• A shrub swamp;
• Creation of three channels enabling year round water circulation, particularly in winter;
• The marsh enabled the restoration of fish spawning, nursing and feeding activities and generate habitats suitable for other species, including birds.

Project Characteristics for Plants and Wildlife:

• Before the work began, the brown snakes were captured and relocated outside of the work site;
• Nearly 500 trees were cut and the majority of them were invasive species;
• At the end of the work, there was a complete re-vegetation of the site;
• Planting of 75 plant species, including trees, shrubs and aquatic plants indigenous to the Montréal area;
• A turtle beach was created at the edge of the marsh.

Environmental Benefits of the Project

The Lapierre Island restoration project resulted in many environmental benefits:

• Restoration of a site damaged since the 1980s;
• Rehabilitation of the existing bridge;
• The configuration of the development aims to optimize the use of the marsh by fish at all life stages, including the Bridle Shriner (vulnerable) and the Copper Redhorse (threatened);
• The project could improve fishing conditions in the Rivière des Prairies area;
• Increase of biodiversity on Lapierre Island and the surrounding area;
• Diversity of wildlife (birds, reptiles and amphibians, and mammals) could benefit from the site;

Mitigation Measures During the Work

The implementation of Lapierre Island development could cause inconveniences to the Island's wildlife and citizens residing near the work site. For this reason, Infrastructure Canada requires that contractors take over 100 mitigation measures, including:

Noise Management:

• Municipal and provincial noise regulations must be respected;
• Where possible, noisy equipment will be placed far from residences;
• Adjustable volume back up alarms will be installed;
• The idling of gasoline-powered equipment and vehicles will be minimized;
• The impacting noise caused by the rear panels of dump trucks will be avoided.

Traffic:

• The contractor must establish a truck traffic plan in collaboration with the district of Rivière-des-Prairies–Pointe-aux-Trembles;
• Limit machinery traffic on roads recommended by the City, and prohibit heavy machinery traffic outside of designated areas within the Island;
• A flagger will be present at all times during work near Gouin Blvd.

Air Quality:

• Municipal and provincial thresholds regarding air particles must be respected;
• Sealed or standard dump trucks will be covered with a tarp to limit the dispersion of fine particulate matter in the air;
• Cleaning of Gouin Blvd. as needed;
• A truck wheel cleaning area will be set up at the site's exit to prevent dirt on the road network.

Natural Environments:

• Dry work areas will be required in the river in order to prevent generating suspended solids;
• The use of sediment barriers will be required around the site;
• The clearing work will not be carried out during the nesting period, i.e. from mid-April to late August;
• The water excavation and bridge rehabilitation work will not be carried out during restricted periods for fish, i.e. from April 1 to September 1.