The scope of work associated with this RFQ includes but is not limited to the supply of all materials, labour, and installation associated with Stage 1 Enabling Works -Tunnel Rehabilitation and includes excavation, concrete removals, concrete structural repairs, waterproofing, and backfilling. All work must be coordinated with utility installations to ensure the protection of existing infrastructure.
This project includes work on segments of two tunnels: Segment 1 (South Tunnel) and Segment 2 (North Tunnel). Segment 1 runs east-west across the site from Howlett Street to Leggett Avenue. Segment 2 runs east-west from Building M-21 to Howlett Street. Rehabilitation work on these tunnels occurs near the intersection of the existing roads and tunnels. Three areas are included: Reinforcement Area A and B (Tunnel Segment 1) and Reinforcement Area C (Tunnel Segment 2). A high-level overview of the work to be performed is as follows—note the scope and quantities below are subject to change, pending the issuance of the RFP:
- Tunnel Segment 1
- Size of existing tunnel—1620mm (width) x 2365 mm (height).
- Reinforcement Area A – 9,200 mm long, located under Legget Avenue.
- Reinforcement Area B – 11,000 mm long, located under Howlett Street . New storm and sanitary to cross under Reinforcement Area B. The design, installation, maintenance, and removal of temporary shoring for the existing tunnel are required as part of this project.
- Tunnel Segment 2
- Size of existing tunnel – 1620 mm (width) x 2285 mm (height).
- Reinforcement Area C – 11,350 mm long, located under Howlett Street. New storm and sanitary to cross under Reinforcement Area C. The design, installation, maintenance, and removal of temporary shoring for the existing tunnel are required as part of this project.
- Work on Reinforcement Areas (A, B, and C) includes but is not limited to:
- Cap Slab—Remove existing waterproofing and protection board and scarify concrete surface 25 mm on existing cap slab. Remove delaminated and deteriorated concrete as directed by the construction manager. Rehabilitation includes installation of dowels and reinforcing steel and casting 325 mm depth of concrete in the top slab in segments matching expansion and construction joints in existing tunnels. It also includes sealing the joints in the new slab, installing waterproofing and protection boards, and installing a 50 mm packed sand cushion over the protection boards.
- Walls—Remove existing mastic asphalt damp proofing and scarify/scabble walls 10 mm minimum. Remove delaminated and deteriorated concrete with a minimum depth of removals of 50 mm. Abrasive blast clean walls during removals. Rehabilitation includes a concrete refacing of a depth of 250mm and waterproofing and protection board.
- Footing – Install new tunnel footing 400 mm x 400 mm.
- Drain Pipe – Remove the existing drain pipe and install a new 100 mm DIA perforated drain pipe and connect it to the existing pipe to make it continuous.
