T1Clean Heat Central Utility Plant Decarbonization Project – Geoexchange Test Boreholes

Notice of Intent – T1Clean Heat Central Utility Plant Decarbonization Project – Geoexchange Test Boreholes

Public Comment Period on Intent to Make a Determination

August 26, 2026 – The Greater Toronto Airports Authority (GTAA) must determine whether the proposed T1Clean Heat Central Utility Plant Decarbonization – Geoexchange Test Boreholes Project located at Toronto Pearson International Airport is likely to cause significant adverse environmental effects. To help inform this determination, the GTAA is inviting comments from the public respecting that determination. All comments received will be considered public. For more information, individuals should consult the Privacy Notice on the Registry website.

Written comments must be submitted by September 26, 2026 to:

Greater Toronto Airports Authority

3111 Convair Drive; Toronto AMF, ON; L5P 1B2

Email address: environment@gtaa.com

Proposed Project: T1Clean Heat Central Utility Plant Decarbonization Project – Geoexchange Test Boreholes

This project involves the following:

As part of the Greater Toronto Airports Authority's (GTAA's) Toronto Pearson Airport Longterm Investment in Facilities & Terminals (LIFT) Program, GTAA is evaluating a geoexchange system to support the future decarbonization of heating and cooling systems at Toronto Pearson International Airport.

The proposed project consists of constructing and testing three geothermal test boreholes on developed federal airport lands in the vicinity of the Central Utility Plant at 3255 Elmbank Road, Mississauga, Ontario which consisting of paved surfaces, utility areas, and previously disturbed lands.

The test-borehole program will evaluate drilling feasibility, subsurface conditions, ground thermal properties, thermal performance, and the constructability of deep vertical and angled geothermal boreholes. The information obtained through the program will support the design and environmental evaluation of a potential future geoexchange borefield.  The test boreholes are intended to remain in place following testing and, if confirmed to be suitable, may be incorporated into the future geoexchange system.

Project activities are expected to include:

• Surveying and confirming the test-borehole locations
• Utility locating and preparation of the drilling work areas
• Mobilization and operation of geothermal drilling equipment
• Drilling one vertical and two angled test boreholes
• Installation of the polyethylene U-loops
• Bottom-up placement of thermally enhanced grout
• Pressure and flow testing of each installed U-loop
• Completion of a 48-hour thermal-conductivity test on each borehole
• Documentation of geological formations, groundwater conditions, drilling observations, and thermal-test results
• Management of drilling water, cuttings, and other drilling materials
• Demobilization and restoration of the affected work areas.

Several sustainability best practices will be incorporated into the projects design and implementation for the wider Toronto Pearson Airport Longterm Investment in Facilities & Terminals (LIFT) Program.