Betty Lake Water Treatment Plant Upgrade, Canada
The Betty Lake Water Treatment Plant at CFB Wainwright was upgraded with a filtration system and an immersed membrane system in 2009.
The plant has been operational since 1957, and it provides around 80% of the treated drinking water to the town of Wainwright and the remaining 20% to a Canadian army base near Wainwright. The upgrade improved the quality of drinking water for both regions.
The primary water supply for the plant is Battle River, a major tributary of the North Saskatchewan River. The filtration system helps treat approximately 1.4 million cubic metres of water annually.
The estimated investment for the filtration system was $11.4m, and the upgrade included installation of a 192m² GE immersed membrane system.
Treating vast amounts of water
Water from the Battle River is pumped up to Betty Lake via a 2.2km pipeline, which carries 1.4 million cubic metres of water every year.
A multibarrier approach established at the plant features a series of barriers that prevent monitor water forpathogens. These barriers assist in the protection of source water, treatment, and distribution system integrity, providing a set of alarms to warn of reduced water quality.
The Department of National Defence (DND) identified the need for an additional barrier to ensure safe supply of drinking water and proposed an addition to the water treatment plant for an immersed membrane system that uses ultra-filtration (UF) membranes.
Graham Construction and Engineering of Edmonton was awarded the $5.3m contract for the upgrade project, which saw the installation of this additional barrier. This approach filters pathogens in raw water, particularly high concentrations of Giardia cysts and Cryptosporidium oocysts. These consist of pores with a sizes up to 7µ. The UF membrane system typically has a pore size of 0.01µ, which prevents the passage of pathogens.
The immersed membranes serve as a polishing step in the water treatment process after the existing dual-media filters. Since the UF membrane system cannot eliminate all viruses alone, chlorination is still used in the final treatment process.
The operation of the plant starts with pumping the raw water from the Battle River to the Betty Lake through the constructed membranes into the centre of the straw which is sent to the tank and chlorinated. The finished product is 99.999% free of cysts and oocysts.
The immersed membrane upgrade results in additional process waste, released into the south lagoons. Process waste evolves from the immersed membranes following back pulsing, maintenance cleans, and recovery cleans.
Waste generated from these three processes collectively mixes with the waste from the existing water treatment plant.
These waste streams reach the Betty Lake through the existing south lagoon.
The entire wastage is either channelled to north slough or back to Betty Lake depending on the nature of the filtration process.
To comply with an alternative method to manage the current and future waste streams, the DND planned the plant upgrade to include improvement and construction of well-designed and engineered lagoons.
The best method to handle, treat and dispose of the process waste was reviewed based on the technical, environmental, operational, construction and financial requirements.
The engineered lagoons for the effluent management were planned to be built within a year of the completion of the immersed membrane system. In September 2011, the DND, however, proposed construction of a new effluent management system by 2013.
It is planned with three effluent ponds - lime alum sludge pond, filtration waste and a clarifier cell pond to treat the effluents. The ponds will be built in the footprint of the existing lagoons and progress only after an environmental assessment.
The effluent clarifier outlet is also planned to include a tideflex check valve for discharging into Betty Lake.