Okotoks Water Treatment Plant Flood Protection

The 2013 flood tore through the Sheep River Valley, damaging critical infrastructure at Okotoks’ water treatment plant (WTP), isolated the plant, and challenged operator access. The plant had been built above standard flood levels but there was no freeboard protection and the water came within inches of the main floor slab. When the flood waters receded, the damage revealed that the flood risk at the site wasn’t limited to water inundation.

Our flood risk assessment used historical aerial imagery, LiDAR generated terrain surfaces, photographs from the flood, hydraulic modelling, high water marks, and investigation of the effects from recent floods to identify the geomorphic changes that could occur during a flood event. The investigation revealed several flood channels in the WTP well field that could avulse and cut the power and communication lines to the wells. Two prominent sub-channels exhibited avulsion during the event. If the flood duration was long enough for those processes to continue, there was a risk that the Sheep River main channel would switch in its floodplain and flow around the WTP building. This could have severe consequences to the integrity of the building and erosion protection was warranted.

With the help of our team, the Okotoks WTP is now better equipped to withstand an extreme flood event.