Annacis Island Wastewater Treatment Plant – Phase 1 Stage 5 Expansion

The Annacis Island Wastewater Treatment Plant (WWTP) is the largest secondary treatment plant in Metro Vancouver. Originally built in 1975, its capacity of 575 ML/D serves approximately 1 million people in 14 municipalities. Metro Vancouver initiated the Stage 5 Phase 1 expansion project to allow the plant to treat the flow from an additional 250,000 people.

Graham and its joint venture partner were contracted perform the construction scope which includes extensive ground improvements to address seismic code provisions, the construction of new primary treatment facilities, modifications within existing grit dewatering facilities, modifications within the existing primary gallery, modifications to the existing primary influent channel and inlet gates, construction of new solids contact tanks and associated channels and piping, modifications to the existing solids contact tanks and associated channels, and construction of Trickling Filter bypass piping. It also includes the extension of the existing gallery in the secondary treatment area, construction of new, and adjustment of existing, secondary clarifiers and associate channels and equipment rooms.

Modifications to the existing primary odour control facility and to the existing secondary odour control facilities and construction of a new primary odour control building were also part of the scope, as were extensive electrical expansion and upgrades, along with a new utility tunnel between the existing Influent Pumping Station and new primary area electrical building.

Graham and its joint venture partner were also responsible for the testing and commissioning of the new components of the plant. Commissioning was performed as the work sequences were completed.

The plant remained operational throughout construction.