Take a Virtual Tour of Saskatoon's Water Treatment Plant:
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Avenue H and 11th Street
The Water Treatment Process (pdf)
Water is taken directly from the South Saskatchewan River through newly commissioned (2012) intakes upstream from the Water Treatment Plant. The raw water is screened and then pumped to the Water Treatment Plant with 900 hp variable-speed vertical turbine pumps. These pumps provide an initial capacity of 350M liters/day, with the capacity to expand to 545M litres/day for future needs. Back-up intakes and low lift pumps, also located at the Water Treatment Plant, are only used during maintenance shutdowns and emergencies.
The design capacity of the intake facility will secure high quality raw water that will meet the water supply needs and the long-term capacity requirements for a projected population of 500,000 supplied from both the Avenue H Water Treatment Plant and a potential future East-Side Water Treatment Plant.
Image of Raw Water Intake (and Circle Drive South Bridge) under construction:
Used only when the Low Lift is active, this chamber removes large debris such as wood from the water and allows some sand to settle out. This facility received a full upgrade in 2010 and is operating very efficiently. Low Lift Station
Seven different pumps, including two emergency pumps provide raw water to the Water Treatment Plant as a backup during power failures.
Water from the low lifts are moved through large cyclonic separators to remove smaller particles of sand down to 75 microns. Potassium permanganate is added to the raw water prior to the clarification process. Potassium permanganate is used to eliminate taste and odor problems caused mainly from organic constituents.
The water then enters the clarifiers, where it is mixed with ferric sulphate and lime. Lime reacts with the hardness in the water to form insoluble carbonates and hydroxides that settle out in the process. Ferric sulphate reacts with particles in the water and the lime to coagulate into a large particle (floc) which becomes heavier than the water and settles out. This process is called floculation.
The clarifier floc concentration is carefully controlled and maintained as a dense circulating slurry. The clear water is drawn off the outer top of the clarifier through radial launders, while the floc settles and concentrates in the center mixing zone of the clarifier. Excess sludge is flushed back to the Residuals Management Facility. Water quality is monitored under these carefully controlled conditions.
Chlorine Contact Basin
Chlorine & sodium silico fluoride are added just prior to the water's entrance into a large contact basin. Chlorine is added to disinfect the water while fluoride is added to assist in the prevention of tooth decay. The contact basin provides the necessary time for disinfection reactions and further clarification through settling. Filtration
The water is then filtered through dual media filters (sand and crushed coal [anthracite]). The filtration rates are carefully controlled in attempts to maintain water turbidity of less than 0.1 NTU.
Following filtration, ammonia hydroxide is added. The ammonia combines with the free chlorine (previously added) to form chloramines. Chloramines have a lower disinfection capability than chlorine but remain active for a much longer period of time. This extended activity permits disinfection to continue throughout the distribution system.Clear Well
Once the water has passed through the filters, it is retained in the clear well storage beneath the Water Treatment Plant . This water is used for backwashing filters and supplying finished water to the high lift pumps. The Avenue H Reservoir is across the street from the Water Treatment Plant and is used as an extension of this clear well.
High Lift Station
The high lift pumps draw the treated water from the clear well and pump it to the distribution system. The pumps maintain a pressure of 690kPa or 100psi in the domestic water lines that they feed. The high lift pumps also move the water to the reservoirs.Reservoirs
The City of Saskatoon currently has two water reservoirs, for use when the demand is greater than the plant output. They are located on Acadia Drive and on 42nd Street. These two reservoirs are filled by the high lift pumps and have their own pumps to supply pressure to the distribution system. When pumping out of the reservoir, each reservoir has a pumphouse to pump water back into the distribution system. The pumps in the reservoirs can also be used as booster stations to continue to supply water at the appropriate pressure to the City.Residual Management Facility
Residuals from the backwash water, filters, clarifiers, and chlorine contact basin go to two sumps in the basement of the facility. Residuals are concentrated in a thickener where the residual is concentrated by removing water in a similar process to the clarifiers. The concentrated residual is pumped to two filter presses where the remaining water is pressed out of it. The solid filter cake is removed and hauled by truck to the Saskatoon Landfill. The water from the thickener and the filter presses are returned to the back wash water sump. This water is pumped to a clarifier in the facility where clear water comes off the top and is dechlorinated before it is returned to the river, the sludge produced from this part of the process is returned to the residuals sump.
Saskatoon was incorporated as a village in 1901, and by 1903 had a population of 113. The next few years brought a rush of settlers into the district, and by 1906 the population grew to 5,000 making Saskatoon a city.
It was in that year that a combined power plant and water treatment plant was built at Avenue H and 11th Street, the site of the present Water Treatment Plant. Steam-driven pumps were used to raise the water from the river to a clay-lined sedimentation basin and detention chamber. The water was then drawn from the basin and pumped directly to the City mains by a steam driven high lift pump. In 1910 and 1911, new electrically-driven centrifugal pumps were installed and a fully equipped rapid sand filtration plant was built. This original filter plant, although upgraded in many ways, is still in service today. The Water Treatment Plant has undergone numerous improvements and expansions to serve the growing population and increasing demand for water from both the industrial/commercial and residential consumers. The most substantial growth period has been in the years following 1948, in which the plant capacity has more than tripled.