YMX - Aircraft hangar construction and tarmac extension at Mirabel

Notice of Determination

October 19, 2026 – ADM Aéroports de Montréal has determined that the project for the construction of aircraft hangars and tarmac extension at YMX Mirabel is not likely to cause significant adverse environmental effects by applying the mitigation measures provided for in the project.

This decision is based on the following factors:

• Mitigation measures that are technically and environmentally feasible below;
• Community knowledge;
• Knowledge and impacts on the rights of Indigenous peoples.

The mitigation measures considered in this determination are as follows:

Vegetation

• Clearly delineate work areas to avoid trampling and machinery traffic outside of these areas.
• Control the spread of invasive species by cleaning machinery and equipment.
• Properly separate and manage soils containing invasive species.
• Quickly revegetate disturbed areas after the work.

Surface water quality

• Install sediment barriers and other erosion control devices.
• Protect catch basins and storm systems.
• Quickly stabilize bare soils.
• Manage pumping and runoff water before it is discharged.
• Regularly monitor the quality of the water discharged.

Water quality in the construction and operation phases

• Install a functional drainage system directing water to treatment structures.
• Inspect and maintain oil-water separators, sumps and lines.
• Store oils, fuels and chemicals in secure areas with containment.
• Maintain spill response kits.
• Clean up immediately in the event of a spill.
• Properly maintain equipment to avoid leaks.

Soils

• Carry out environmental characterization of soils before excavation.
• Segregate soils according to their level of contamination.
• Carry out the management and disposal of the soil in accordance with the applicable regulations and ensure their traceability via the Traces Québec system.

Hazardous materials and spills

• Develop an environmental incident response plan.
• Maintain spill kits on the job site.
• Store hazardous materials in secure areas.
• Provide retention pans for fuel tanks.

Air quality and dust

• Water surfaces and piles of materials when necessary.
• Use dust suppressants that comply with BNQ standards.
• Limit speed on the construction site.
• Avoid idling vehicles.
• Maintain machinery in good condition.

Residual materials and GHGs

• Reuse, recycle or reclaim construction waste before disposal.
• Reduce travel and energy consumption on the construction site.
• Promote alternative fuels and low-emission equipment.

Accordingly, ADM Aéroports de Montréal may exercise its powers to enable the project to be carried out.