Bessac and its joint venture partner Pomerleau Inc, has been awarded a CA$184 million contract by Metro-Vancouver to construct a new outfall pipeline from the Annacis Island Wastewater Treatment Plant (WTP) to the Fraser River, in Vancouver, Canada.
The scope of works for the project consists of the construction of two 40m deep shafts, one at 15m and one at 10m diameter, inside the WTP; two 4.20m internal diameter segmentally lined tunnels (200m and 580m long); a river riser in the Fraser River; a 280m long, 2.5m diameter, diffuser buried in the Fraser River bottom; and a new water control structure.
The Annacis Island Wastewater Treatment Plant is one of the region’s largest wastewater treatment facilities. Metro Vancouver is increasing the capacity of the current facility to meet the needs of the region’s growing population.
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 the 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.