New Bonnybrook Wastewater Treatment Plant Treated Effluent Outfall—Design, Contracting, and Construction Overview

The Bonnybrook Wastewater Treatment Plant (BBWWTP) is one of the largest cold weather BNR plants in the world undergoing a significant expansion, including a new outfall to discharge all treated effluent into the Bow River. The BBWWTP currently discharges all the treated effluent flow into the Bow River via a conventional bank outfall. The new outfall is not only required for plant expansion but also is an integral part of a flood protection plan for the site. Design of the outfall system was focused to strike a balance between flood protection capabilities, upsize for expected flow increase to year 2076, environmental enhancement, and cost. The outfall is designed to convey 1,962 MLD (22.71 m³/s) (518 MGD) to a new exfiltration style diffuser under the bed of the Bow River. Construction of the new outfall is ongoing and scheduled to be complete by the end of 2021. The presentation will discuss the project drivers and motivations, some of the key design and construction challenges, and contracting strategy used to deliver this infrastructure.