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Project Profile1 min read

Bonnybrook Upgrade to Box Culverts

Upgrades to Bonnybrook WWTP with Precast Concrete Box Culverts

By: Tyson Dyck, P. Eng., Technical Marketing Engineer, Inland Pipe 

Inland Pipe is supplying precast concrete box culverts and other drainage structures to the City of Calgary’s Bonnybrook Wastewater Treatment Plant (WWTP) expansion project. The expansion will involve multiple construction phases over 10 years and cost taxpayers $CAD800 million. The Bonnybrook WWTP services the entire Northern half of Calgary and has the capacity to treat wastewater for a population of 946,000. When the expansion is completed, its capacity will increase to a population of 1,370,000, which is estimated to support the city’s rapidly growing population until the mid-2030s. In addition, the City is improving the energy efficiency of the facility by capturing biogas from the treated wastewater to generate electricity. During certain times of the year, the plant can operate entirely from its own biogas, thereby significantly decreasing operating costs.

Four parallel 1800mm (72-inch diameter) reinforced concrete pipe diffusers are installed on the Bow River riverbed. The pipe was directly designed with integral stainless steel diffuser ports.
Two parallel 3m x 3.6m (10 feet x 12 feet) gasketed box culverts are being installed to extend the outfall downstream of the Bonnybrook WWTP. A third 2.4m x 2.4m (8 feet x 8 feet) box culvert is being installed alongside.
Calgary’s 2013 flood caused $CAD13.5 million in damages to the Bonnybrook WWTP, which is why the expansion includes flood protection upgrades. A new berm is being constructed along the riverbank adjacent to the plant to prevent overland flooding. The flood showed that surging water could flow into the plant through Bonnybrook’s two outfall channels. To prevent this situation from re-occurring, precast concrete box culverts are being installed one kilometer downstream of the plant. Additionally, unlike the present outfall channels that are situated on the riverbank, the new outfall channels will be located on the bed of the river. Installation on the riverbed will help with flood resiliency and improve the diffusion of the effluent in the Bow River. Graham Construction is the General Contractor for this project, and KLS Earthworks is installing the box culverts. Whissell Contracting is installing the pipe diffusers.
Special box bends were supplied by Inland Pipe for the outfall upgrades.

Photos: Courtesy of Inland Pipe