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Soil & Groundwater - Environmental Impact Assessment Report

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Key Findings

  • The Study Area consists primarily of gravelly sand, gravel, silt, clayey silt, silty clay, sand and silty sand.
  • The following source water features are relevant to the Study Area: an Intake Protection Zone*, a regional Highly Vulnerable Aquifer** and an Event Based Area***.
  • The area is serviced by municipal water supply from Lake Ontario.
  • Without mitigation, there is potential for impacts to groundwater (e.g., temporary drawdown of the water table) and soil (e.g., ground movement and settlement as a result of excavation). The completion of hydrogeological and geotechnical investigations and a construction dewatering assessment during detailed design, completion of groundwater and soil management plans as planning progresses, and implementation of appropriate mitigation measures during Project activities are anticipated to reduce potential impacts (see Potential Effects & Mitigation Measures).

* Areas of land and water that contribute source water to a surface water drinking system intake.

** An aquifer (underground layer of permeable soil and/or rock) susceptible to contamination due to its location near the ground surface or the surrounding soils.

*** Areas in a watershed where a spill could pollute the drinking water supply.

Potential Effects & Mitigation Measures

Potential Effects


  • Construction activities will cause displacement of soils and bedrock. This may result in ground movement and settlement.
  • Construction activities could expose pre-existing contaminated materials and/or result in the spreading of contaminated materials.
  • Construction dewatering may impact private groundwater supply wells and groundwater-dependent natural features.
  • Construction activities have the potential to affect groundwater quality through contaminant releases.


  • Impact to soil and groundwater and not anticipated during operations.

Mitigation Measures


  • Develop a Soil and Excavated Materials Management Plan for the handling, management and disposal of all excavated materials that is generated or encountered during construction.
  • A Spill Prevention and Response Plan is required to be developed prior to initiation of construction activities.
  • Conduct dewatering such that ground loss is controlled/minimized.
  • Site-specific mitigation measures and monitoring programs related to potential groundwater impacts will be determined prior to work commencing.


  • As no impacts are anticipated during operations, no mitigation measures are recommended.

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Submissions are closed.