E.L. Smith Water Treatment Plant operations

The water treatment process includes coagulation, flocculation, and filtration and uses free chlorine, chloramine, and UV light for disinfection.

The intake structures for the water treatment plant are located in the deepest part of the North Saskatchewan River, near the lowlift pump station. They're situated below the water surface so oil and floating debris pass over them. Additionally, the intake structure at the E.L. Smith water treatment plant is designed with a fish return system to gently deposit fish downstream.

Screens are located just before the lowlift pumps to strain out debris which may enter the intake pipe. The screens are designed with holes about one square centimetre (cm) which keep out fish, sticks, and leaves. They're rotated and periodically cleaned using back wash water to return debris to the river.

Alum and powdered activated carbon are the first chemicals added to the water. These chemicals are added by feed pumps which are adjustable to supply the correct dosages.

The lowlift pumps get their name because they pump at a high volume but at "low" pressure. They're approximately 1,000 horsepower and pump at a rate of 20 – 200 millions of litres per day (MLD).

When the chemicals are added, it is necessary to mix them thoroughly with the water. High intensity mixing is done at the lowlift pump station or in a mixing chamber.

Following rapid mix, polymer is added and the water is then slowly mixed to encourage the formation of floc. Floc (large jelly-like particles) results from the attraction of dirt particles to the chemicals alum and polymer. The floc later settles out of the water by gravity.

After the floc is formed, it is then allowed to settle to the bottom of a clarifying basin. This is the process of sedimentation. Once the dirt-laden floc settles to the bottom of the basin, sludge is removed and the clear water is decanted from the surface.

Free chlorine (0.8 % Sodium Hypochlorite) is added after clarification to kill harmful bacteria and other microbes. After filtration, the water passes through ultraviolet (UV) disinfection that renders the micro-organisms harmless. Ammonia is then added and combines with chlorine to form a long-lasting disinfectant called monochloramine.

The water is filtered by allowing it to slowly flow down through a layer of anthracite coal (about 50 cm) and a layer of sand (about 30 cm). The filters are regularly cleaned by pumping air and water back up through the sand and anthracite coal to dislodge any accumulated particles.

After filtration, the water goes into on-site reservoirs where it is stored until required. The reservoirs provide additional time for disinfection and also allow the treatment plant to handle variations in water demand throughout the day.

Sodium Bisulphite (SBS) is added to all the chlorinated waste streams to ensure complete de-chlorination before they're returned to the North Saskatchewan River.

Highlift pumps get their name because they are required to pump water at "high" pressure. These pumps are each 2,000 to 4,000 horsepower and pump 90 – 200 MLD at a pressure of about 150 pounds per square inch (psi).

We along with our project partner, Associated Engineering, won an Alberta Emerald Award for environmental leadership related to innovative upgrades to the E.L. Smith water treatment plant.

The design protects the environment while significantly increasing the Edmonton capital region's supply of clean drinking water over the long-term.

By reusing existing infrastructure that may have otherwise been decommissioned, the upgrades increased the plant's water production capacity by 150% while increasing the plant's footprint by only 25%.

The design also included an award-winning environmentally-friendly water disinfection system and the construction of a water intake system that diverts and returns fish safely downstream of the plant, and as a result, is preserving aquatic life in the North Saskatchewan River.