Betty Lake Water Treatment Plant Upgrade, Canada
Betty Lake Water Treatment Plant at CFB Wainwright was upgraded with a filtration system and an immersed membrane system in 2009. It improved the quality of drinking water for both the military base and the adjacent town of Wainwright.
The estimated investment for the filtration system was $11.4m. The upgrade included installation of the GE immersed membrane system. The 16m x 12m system comes up to the south of the existing plant on a total area of 192m².
The Betty Lake Water Treatment Plant has been operational since 1957. The plant provides about 80% of the treated drinking water to the town of Wainwright and the remaining 20% to the Canadian Forces Base Wainwright. The upgrade improved the quality of drinking water for both regions.
The primary water supply for the plant is the Battle River, a major tributary of the North Saskatchewan River. The filtration system helps treat approximately 1.4 million cubic metres of water annually.
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.
The multibarrier approach used at the plant involves establishing and maintaining a series of barriers that prevent pathogens. These barriers assist in the protection of source water, treatment, distribution system integrity, monitoring water quality and adverse water quality alarms and response.
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 upgrades project. After this upgrade, the plant is able to provide an additional barrier in the water treatment process. This multibarrier approach filters pathogens in raw water, particularly high concentrations of Giardia cysts and Cryptosporidium oocysts, ensuring the safe supply of drinking water.
The Giardia cysts and the Cryptosporidium oocysts found in the water consist of pores with a size of one -seven microns. The ultra-filtration membrane system typically has a pore size of 0.01 microns. This 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 three operations - 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.
In order 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.