French firm wins build contract for B.C.’s Annacis Island WWTP expansion

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Paris-based VINCI Construction has won a $184-million contract to build new pipelines as part of an expansion for British Columbia’s Annacis Island Wastewater Treatment Plant.

The plant, which treats wastewater from 14 municipalities across the Lower Mainland to be safely released into the Fraser River, is increasing the capacity of the current facility to meet the needs of the region’s growing population. The facility is one of the region’s largest, with a treatment capacity of nearly 175 million cubic metres per year, equivalent to the demands of a population of one million.

Some 20 projects are part of the expansion and could total more than $750 million.

VINCI Construction’s (subsidiary Bessac) partnership with Pomerleau Inc. will aim to build two 40-metre deep access shafts with 16- and 7-metre diameters, respectively, and two segment-lined tunnels with lengths of 580 and 200 metres and an inside diameter of 4.2 metres.

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In relation to the new contract, Bessac’s management made the following statement: “This is Bessac’s first contract in British Columbia, a Canadian province offering excellent prospects for the future. Bessac (Soletanche Bachy) specializes in tunnel and microtunnel construction and works on complex projects both within and outside France.”

The contract also includes construction of a riser in the Fraser River and refurbishment of the existing diffuser, following commissioning of the new 280-metre long diffuser buried in the riverbed. A new water control system will also be connected to the existing structures. 

Other upcoming projects at the plant include new trickling filters, secondary clarifiers and a cogeneration facility to make better use of green energy captured on site, according to a synopsis of the project. Additional upgrades include repairing or replacing older parts of the existing plant; strengthening the plant to reduce the impacts of earthquakes; improving existing odour controls; and building a more reliable backup power source.

A new outfall pipe is also planned. It’s described by project co-ordinators as “the final link in a long chain of interconnected parts of the wastewater treatment system.” A tunnel approximately one-kilometre long will be constructed from the plant to the river, where a diffuser system will be installed. 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.

The last expansion at the plant took place in 1998. The new construction is expected to be completed by 2023.

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