New outfall tunnel for Ashbridges Bay Wastewater The construction of the new outfall tunnel for Ashbridges Bay Wastewater Treatment Plant in Toronto has been a work in progress since the inception of the project last year. The wastewater treatment plant outfall is the point at which the effluent (the fully treated wastewater) is discharged back into Lake Ontario. The new outfall tunnel will improve water quality at the city’s shorelines and beaches after completion. The purpose of the new outfall tunnel is to increase its capacity and better convey the effluent from the Ashbridges Bay Treatment Plant (ABTP) into Lake Ontario, as well as to better operate under high flow conditions, mainly during rainstorms.It  will replace the existing outfall, constructed in 1947, reaching the end of its service life. According to the construction notice released by the City of Toronto in January 2019, the outfall project includes: •    a 14 m diameter shaft, approximately 85 m deep; •    a 3.5 km long, 7 m diameter outfall tunnel, mined through rock beneath the Ontario lakebed from the Ashbridges Bay Treatment Plant in east-endToronto; •    50 in-lake risers (vertical stainless-steel pipes) extending from the tunnel to the lake bed, along the final 1 km of the tunnel. They will disperse treated and disinfected effluent into Lake Ontario.The risers are drilled from in-water barges.The marine construction (risers),  the shaft  and the starter tunnel are almost complete. Tunnelling with the a Robbins Single Shield TBM, manufactured in Mexico, arrived in Toronto last June and whose assembling is on going, is expected to start later this fall. As the tunnelling work advances, the tunnel-riser connection work will be performed from the tunnel. However, all the risers have to be installed and pressure tested before the TBM mining advances to within 100 m of any riser. The tunnelling contractor is Southland Mole of Canada/Astaldi Canada Joint Venture and the consulting engineering team is comprised of lead consultant Hatch and Jacobs (formerly CH2M) and Baird. The entire project is expected to be completed in the winter of 2024 visit http://www.toronto.ca/. 31/20. To see the construction notice click this link - https://www.toronto.ca/wp-content/uploads/2019/01/96c8-ecs-info-w14-ashbridgesbay-outfall-cons-jan10-18.pdf To see a video of the project click here - https://www.youtube.com/watch?v=1IHOiDZJxy0&feature=youtu.be