Bonnybrook Wastewater Treatment Plant - Plant D Expansion Flood Protection

Causing extensive damage to public and private infrastructure alike, the 2013 flood was a momentous event in Alberta’s history. A critical piece of municipal infrastructure, the Bonnybrook Wastewater Treatment Plant (WWTP), was damaged in three significant ways: overland flows from the river, flooding due to surcharging of the sewer system, and high groundwater levels. To address each of the sources of site flooding, we developed a number of flood mitigation measures which were completed as a component of the Bonnybrook WWTP Plant D Expansion project.

The first of these measures features an 830-metre long and 3.5-metre high earth flood berm along the east boundary of the Bonnybrook WWTP site to prevent overland flows from the river. Addressing the flooding caused by surcharging of the sewer system, we relocated multiple storm sewer pipes, removing an existing storm outfall and re-routing trunk sewers. To prevent the back-up of river water levels through the WWTP outfall, the existing treated effluent bank outfall was relocated approximately 650 meters downstream. The final measure our team developed was a groundwater dewatering system, including a groundwater dewatering pipe, to reduce the impacts of high groundwater levels on existing structures and the site as a whole.

No longer vulnerable to neighboring Bow River, the Bonnybrook WWTP can continue to provide necessary services for years to come.