Once it has been treated, wastewater from the Annacis Wastewater treatment plant is released into the Fraser River through an outfall pipe. A new outfall location and diffuser system is being installed, which will involve constructing a one-kilometre long tunnel (approximately) from the plant to the river.
The new outfall location and design will ensure that treated effluent is spread out over a broad area underwater to maximize dilution and minimize the impact on the environment.
Once this new pipe is complete it is expected to meet the regional growth needs for the next 100 years while ensuring greater seismic resilience and continuous, reliable and safe management of liquid waste.
Metro Vancouver is committed to minimizing the impacts of this project on the Annacis Island business community and river users. As part of this commitment Metro Vancouver will conduct pre-construction meetings with stakeholders that may be directly affected by the work. Please contact us if you are interested in learning more about this project.
Tunneling the outfall
The new outfall pipe will be excavated using a tunnel-boring machine. This machine will be launched from the entry shaft near the Annacis Island wastewater treatment plant and progress south to the river riser in the Fraser River (see illustration below).