Closed Captioning
Ashbridges Bay Treatment Plant Outfall Video
00:00 Opening screen shows City of Toronto logo
0:03 Ashbridges Bay Treatment Plant Outfall – Don River and Central Waterfront & Connected Projects.
0:08 Cleaning Up Our Waterways: Toronto is embarking on the largest and most significant stormwater management program in the city’s history.
0:15 Don River and Central Waterfront & Connected Projects: With an overall budget of more than $3 billion, this program will greatly improve the water quality in the Lower Don River, Taylor-Massey Creek and along Toronto’s Inner Harbour.
0:28 Ashbridges Bay Treatment Plant: One of the oldest wasterwater treatment plants in Canada and the largest of Toronto's four sewage treatment plants.
0:41 Ashbridges Bay Treatment Plant New Outfall:
A new outfall will be built to replace the existing outfall which has insufficient capacity, does not meet current regulatory standards and is nearing the end of its service life.
(shows a technical diagram of the outfall area in the lake, with components of the outfall including an 85 metres deep,14 metres diameter vertical shaft, near the Lake Ontario shoreline; a 3.5 kilometres long, 7 metres diameter tunnel, mined through bedrock beneath the lakebed; risers, 1 metre in diameter, to disperse treated and disinfected effluent into Lake Ontario)
0:57 Shaft Construction: A watertight shaft is excavated adjacent to the shoreline to support tunneling directly below Lake Ontario. (shows animation of excavation)
1:20 Riser Installation: 50 riser pipes are installed in line with the tunnel extending from the lakebed to just above the tunnel crown.
(shows animation of riser installation)
1:39 TBM Tunneling: A tunnel is excavated below each riser using a Tunnel Boring Machine (TBM)
(shows animation of the tunnel boring machine)
1:59 Riser to Tunnel Connections: 50 vertical in-line risers are connected to the top of the tunnel along the last 1,000 metres of the tunnel.
2:12 Port Installation: After the tunnel is flooded, ports are installed at the top of each riser to improve treated effluent dispersion in the lake.
2:28 On-shore Work: Tunneling operations are supported from a working compound located south of the Ashbridges Bay Treatment Plant.
(image shows a map of Toronto, highlighting the Tunneling Work Zone)
2:39 Mobilization: Initial site works include a new fence, access roads, local utilities, temporary offices, and erosion and sediment control.
2:48 Shaft Excavation: An 85 metre deep on-shore shaft is excavated through soil and rock.
3:04 Starter Tunnel: A starter tunnel is constructed to provide sufficient space to assemble and launch a Tunnel Boring Machine (TBM).
3:11 Off-Shore Work: Off-shore construction is supported from over-water barges and marine vessels located approximately 3 kilometres from the shoreline.
3:30 Off-Shore Work – Riser Shaft Excavation: Barges are mobilized in Lake Ontario to support riser shaft excavation using containment cans and casings.
3:44 Off-Shore Work – Riser Pipe Installation: Riser pipes are lowered into the excavated riser shafts, grouted along their entire depth and then leak-tested.
3:51 TBM Delivery: Major tunnel boring machine components arrive via marine shipping vessel at Port of Hamilton.
4:10 TBM Delivery: Major tunnel boring machine components are delivered to the site at night to avoid traffic interruptions.
4:27 Rear TBM Shield: The first major tunnel boring machine component is lowered into the shaft for TBM assembly.
4:39 TBM Cutterhead: The heaviest tunnel boring machine component (86,000 kg) is safely and successfully lowered to the shaft bottom.
4:53 TBM Assembly: All remaining tunnel boring machine components are lowered into the shaft and the tunnel boring machine is assembled within the starter tunnel.
5:01 TBM Assembly: The tunnel boring machine is moved into the starter tunnel as the remaining tunnel boring machine assembly is completed.
5:13 TBM Commissioning: Tunnel boring machine is fully assembled, operational and ready for tunneling.
5:31 Closing screen shows City of Toronto logo
Consultant – Hatch/Jacobs/Baird
Contractor – Southland Astaldi Joint Venture