Owner
City of Toronto
Client
EBC-Bessac JV
Cost
$380 million CAD
Timeframe
January 2023
— December 2023
Services performed
Design of ground improvement campaign to enable pipejacking construction between drop shafts and the main TBM sewer tunnel. Structural design of the adit-TBM tunnel interface.
Description
The project was implemented by the City of Toronto as a severe wet weather event was experienced on August 19, 2005 which caused widespread basement flooding. In response, the City developed a program to protect basements from future flooding which identified critical areas that were subject to studies. A main storm trunk sewer (Main STS) which extends from the eastern limit in Fairbank Memorial Park to Black Creek in the west was designed. The local collector sewers are connected to the main tunnel via 7 shafts – 4 of those have adit connections to the main tunnel. These vary in depth from 10m to 40m below ground level and in length from 3m to 11m. Dr. G. Sauer & Partners designed a comprehensive ground improvement campaign to ensure the adits could be constructed safely and on time in the challenging varied glacial deposits of Toronto. Dr. G. Sauer & Partners also designed the cast-in-place structural connection between the pipe jacked adit and the main TBM sewer tunnel. Dr. G. Sauer & Partners provided the CJV with innovative alternative design approaches to support the construction.
Geology
Toronto glacial deposits consisting of silty clays, clayey and sandy silts and interconnected lenses of sand.
Location
Toronto ON, Canada
Highlights
- Ground improvement measures developed in collaboration with owners and CJV's designers.
- 4 adits with ground improvement successfully constructed to the bulkhead.
- Geotechnical, structural, and tunnelling methods combined to a tailored solution.
3D model of drop shaft with adit connecting to main TBM tunnel
Geotechnical face mapping of adit connection
Ground Improvement design for adit-main tunnel interface
Adit connection with pipe roof