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Soil & Groundwater - Exhibition Station

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Key Findings


  • Glacial till is the main near surface soil type and is mostly made up of sand and silt.
  • The area is serviced by municipal water supply from Lake Ontario.
  • Construction activities are not anticipated to have significant dewatering requirements.
  • 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 prior to construction, and the implementation of appropriate mitigation measures during construction, are anticipated to minimize potential impacts (see Potential Effects & Mitigation Measures).


Potential Effects and Mitigation Measures


Potential Effects:

  • Subsidence/settlement of structures within the Zone of Influence (ZOI*) due to construction dewatering.
  • Encounter previously contaminated groundwater during construction excavation and/or dewatering activities.

*The Zone of Influence refers to the area where groundwater levels will be lowered due to dewatering.

Mitigation Measures:

  • As part of detailed design, determine water taking quantities, quality, and resultant dewatering ZOI through a site-specific Hydrogeological Investigation, Construction Dewatering Assessment and Groundwater Management Plan.
  • Subsidence/settlement impacts to existing structures can be mitigated with measures such as completion of pre-construction inspections of structures within the dewatering ZOI and implementation of a detailed settlement monitoring program complete with settlement triggers that result in changes to the dewatering program if surpassed.
  • Remedial action plans, risk assessment, and risk mitigation plans for encountering contaminated groundwater.


Potential Effects: 

  • Displacement of soils as a result of construction may result in ground movement and settlement.

Mitigation Measures:

  • Complete a detailed settlement analysis during the detailed design phase.
  • During construction, employ excavation support systems, as required, and/or implement appropriate ground treatment.
  • Develop a Soil and Excavated Materials Management Plan for the handling, management and disposal of excavated material.

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