Treatment Process

Water from the North Saskatchewan River flows by gravity to the river intake building, where it is screened of large debris by the travelling water screen (TWS). The water is then pumped using one of two Low Lift Pumps (LLP) to the Desilting Pond.

This pond is U-shaped and as the raw water is pumped into the pond it makes a slow journey to the other end and slowly settles out more of any suspended sand or silt. The capacity of the Desilting pond is approximately 120 000 m³.

The water that reaches the other end of the desilting pond then flows by gravity back into the building to be pumped by one of 3 700 HP High Lift Pumps (HLP) into the 30 inch diameter steel pipeline that travels 32 kilometers South to the Raw Water Reservoir. 

The reservoir stores the raw water pumped from the river and flows into the Water Treatment Plant by gravity for treatment. The RWR stores approximately 170,000 m³ of untreated water and is located just south west of the Water Treatment Plant.

In case of drought, deteriorating river water quality or accidental pollution the reservoir and the desilting pond can hold enough water to keep up production for a week.

As water enters the plant, the treatment process to create clean and safe drinking water is started. Aluminum Sulfate (ALUM) is added as a part of the coagulation process that helps impurities such as suspended particles, bacteria, and algae lump together. These lumps are called “floc” and will settle in the clarifier. Powder Activated Carbon is also added to remove undesirable tastes and odours.

In the Up-Flow Clarifier floc is created to form a sludge that settles to the bottom of the clarifier. Lime is added to help with the coagulation process and to make the water less acidic, and polymer is added as a flocculent aid to strengthen floc and help it settle. 

The now clear water leaves the clarifier where Chlorine is added. Chlorine disinfects the water by killing bacteria and any harmful organisms and is a crucial element of the treatment process. The final polishing stage is the Dual Media (Anthracite and Sand) filters where any remaining suspended particles in the water are removed. 

Once filtered the clean drinking water enters the 1,200 m3 Clear Well for storage. From here three pumps move the water into the city and the West End Reservoir. The West End Reservoir provides an additional 24,796 m3 of storage for peak water demands, to meet fire flows, and supply the city with water overnight.