Construction of Cawthra Sanitary Sewer and Watermain, Phase 1
Project Highlights
Role: General Contractor
Project Delivery: Design-Bid-Build
Tunnel Equipment: 74” Hybrid Microtunnel Boring Machine
Primary Support: AWWA C302 Concrete Pressure Pipe
Ground Conditions: Mixed and Georgian Bay Formation Shale
Project Description
This contract includes the construction of approximately 1100m of 1500mm diameter sanitary sewer along Cawthra Road (100m by open cut and remaining tunnelled) from Dundas Street East to Bloor Street. The contract also includes the construction of approximately 800m of 400mm diameter watermain along Cawthra Road (100mby HDD and remaining open cut) from Dundas Street East to East of Santee Gate.
The work done includes, but is not limited to, the supply of all necessary labour, plant materials, watermain and sanitary installation, connections to existing sanitary sewers and watermains, all sanitary sewer and watermain appurtenances, sawcutting and removal of asphalt pavement, all excavation and disposal of excavated material, protection of structures below and above ground, protection of utilities below and above ground, placing and compaction of bedding material, placing and jointing asphalt, traffic control, site restoration to existing or better conditions, etc., complete as specified on drawings.
Technicore Underground self-performed the tunnels including setting up compounds, support and sinking of the shafts, and tunnel construction. Technicore as a GC managed subcontractors to complete the rest of the scope which included open cut installation, temporary and permanent traffic signals and surface restorations. Technicore’s sister company, Ewing Fabricators manufactured the AWWA C302 pipe and concrete pressure pipe manholes for this project. Ewing also supported Technicore by fabricating shaft support steel ribs, tunnelling jacking stations, tunnel seals, etc.
Owner: Region of Peel
Start Date: May 2018
Completion Date: May 2021
Drive Length: 965m
Diameter: 1500mm
Consultants: IBI Group
Contract Amount: $11.5 million
Ground Conditions
As per the Geotechnical Data Report (GDR): “Based on the Physiography of Southern Ontario (1984), the surficial geology of the project site is relatively consistent, typically consisting of Late Wisconsinan Age Halton Glacial Till of silty clay to silty sand texture. Within the creek valleys, surficial alluvial deposits of gravel, sand, silt and clay are present overlying the till or bedrock, often with high moisture content and some organic content. Ordovician shale interbedded with limestone and calcareous siltstone of the Georgian Bay Formation lies at 4 to 11m below existing ground surface.” The tunnel was designed to be within Georgian bay formation shale. An area of mixed ground conditions was encountered during the first 200m of mining. The shaft were constructed within the overburden and shale ground conditions.
