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The Hurontario Light Rail Transit Project - Environment

Tree Impacts During Construction 

Metrolinx and Mobilinx recognize that trees are very important and are working closely with the City of Mississauga to help identify planting and compensation requirements for tree removal on both city and private property. Trees will only be removed when necessary.

With major construction comes some impacts to neighboring properties, including the trimming and removal existing trees. On the surface, trees on private property may appear to be outside of the project work zone. This does not mean that neighboring construction activities would not have a negative impact on their survival. It takes a certified arborist, in consultation with the design and construction teams, to determine whether or not construction activities will impact the tree’s survival.

One of the criteria they use to assess the impact of construction on the tree is by measuring the dripline, the area directly located under the outer circumference of the tree branches, from the tree canopy to determine the extent of the underground root system. The dripline marks the extent of the tree protection zone, where fencing is installed to ensure that the tree can be protected during construction. Protective fencing is used to ensure that less than 30% of the root system remains undisturbed by construction activities. In situations where the tree protection zone cannot be protected, an arborist determines that the tree will not likely survive construction. Only then will they recommend the proactive removal of the tree. 

Tree replacements are determined based on municipal permitting guidelines.  One tree will be replanted for each healthy trees that is removed with a diameter at breast height of 49 cm or less. Two trees will be replanted for each healthy tree that is removed with a diameter at breast height of 50 cm or more.

The root system of a tree extends as far as the canopy, this is called the drip line, or tree protection zone.

Environmental Sustainability 

graphic depicting environmental sustainability efforts done on the Hurontario LRT project

From construction to operation, Metrolinx is using environmentally sustainable best practices during all stages of the project. Below are some examples of how we’re working together to build transit responsibly, while minimizing our impact on local ecosystems:

  • As part of a Sustainability Strategy, work is done to ensure the project is climate resilient by reducing energy use and emissions wherever possible. This includes limiting idling by turning off equipment when not in use and keeping equipment properly maintained.
  • Using an Environmental Management System (EMS), we track potential hazards to ensure consistent mitigation and timely follow up.
  • The light rail vehicles (LRVs) for the this project, the Alstom Citadis Sprit, are powered by electricity and emit near zero emissions. This will further reduce air pollution during operations.
  • Dedicated to protecting wildlife and species at risk (SAR), our contractors keep an eye out for any wildlife habitats at all our work sites. Should they encounter wildlife, they work with an ecologist to ensure that construction activities can continue with minimal impact to natural habitats.

Keeping the Worksite Clean 

Maintaining a clean worksite by keeping the areas impacted by our work clear of mud is important. Below are some of the measures we take to control soil erosion and keep our sites and the community clean:

  • Street sweeper trucks are used to clear excess soil, dirt and debris from roadways
  • We use silt fencing around construction areas to keep excess soil contained
  • Silt socks, filled with wood chips are used to trap sediment and stop the soil from slipping onto the roadway or into the storm drainage system.
  • Erosion blankets, made up of mesh netting, hold mounds of soil in place to prevent spillage and spread throughout the worksite, and onto roads and sidewalks

A large water truck sprays a work area to remove dust and debris.