Yellow Quill First Nation
The problems of First Nations water supplies have been much in the news recently. The Yellow Quill First Nation in eastern Saskatchewan had one of the worst situations until their new water treatment...
The problems of First Nations water supplies have been much in the news recently. The Yellow Quill First Nation in eastern Saskatchewan had one of the worst situations until their new water treatment plant opened in 2004.
For eight years before, the community of almost 1,000 people was on a boil water advisory — the longest such advisory recorded in Canada. Their water source at that time was a creek that only ran for one or two weeks a year. To make matters worse, effluent from a sewage lagoon in a community upstream was periodically discharged into the stream.
Associated Engineering and WateResearch were asked to help, first by finding an alternative water source.
The community is located near Greenwater Lake Provincial Park, approximately 300 kilometres east of Saskatoon. The nearest source of high quality raw water was 80 kilometres away — too far for it to be practical or economical to transport the water in.
The Yellow Quill reserve itself had a source of ample groundwater, but previously the quality was considered so poor it had been ruled out. However, the client and engineers decided to experiment with pilot scale processes to see if a way could be found to bring the water in the aquifer up to standard.
The challenge was to find treatment technologies for purifying a groundwater source that was extremely high in dissolved salts, organics, iron, manganese, ammonium and arsenic. It was also susceptible to potential pathogens. The concentration of dissolved solids was in the range of 2000 mg/L. Finding a suitable process was very difficult because of the cold temperature of the aquifer water, which is near 6C all year.
A pilot plant was constructed to test different processes. Conventional technologies such as manganese greensand filtration or other oxidation and filtration processes in combination with membranes were found to be ineffective in the medium to long term. Advanced technologies such as ozonation showed promise, but the floc that was generated resulted in short filter runs. Biological filtration was attractive, but it was feared that the low temperature of the water might reduce the biological activity and compromise its effectiveness.
Taking a holistic view, the team developed an innovative process that incorporates oxidation and integrates biological filtration and reverse osmosis membranes.
The following is the treatment process:
* Oxygen injection for the biological process.
* Biological pre-treatment to remove unwanted compounds such as iron, arsenic and much of the organic carbon based material. One of the key factors in successful biological treatment is the selection of a material to support and house the microbes. At Yellow Quill, the most suitable media was found to be a manufactured expanded clay material that is inert and is expected to last for more than 10 years.
* Reverse osmosis membranes following the biological filters to remove the sulphate, hardness, total dissolved solids and any remaining non-bio-available dissolved organic carbon.
* pH adjustment and stabilization of the water using calcium and magnesium contact. This stage was accomplished through upflow contactors. The method of adjustment was chosen over sodium hydroxide because calcium and magnesium in drinking water promotes better health than high levels of sodium.
* chlorine to provide residual disinfection.
Despite low temperatures the treatment was found to be very effective. Biological activity in the filters is very high, there is low biological and organic fouling of the reverse osmosis membranes, and the contaminants are effectively removed or transformed. The treated water exceeds Saskatchewan, Canadian and American regulations, managing to remove both microbes and microbial nutrients. The membrane provides a barrier against pathogens.
Among the advantages of the process are that it uses up to 20 times less water than manganese greensand filtration, for example. It can withstand variations in water pressure, running 24 hours a day, every day, without membrane “relaxation.” And it is relatively inexpensive, since the filtration material will last 10 years and there is no need for coagulation or pre-oxidation chemicals.
Based on the success of the pilot studies, Associated Engineering proceeded with detailed design and construction of a new treatment plant for Yellow Quill. In the fall of 2003 the project was completed on time and on budget. The operation of the bio-membrane process is stable and robust, with little day-to-day variation, making it easy for band members to operate the plant. The boil water advisory was lifted in 2004, and the plant continues to provide the community with clean, safe water.
The success of bio-membrane filtration in treating this low temperature groundwater bodes well for applying biological tratment to poor quality groundwater sources elsewhere. Similar technology is being used at the Pasqua First Nation in Saskatchewan.
The Yellow Quill Water Treatment Plant won an Award of Excellence from Consulting Engineers of Saskatchewan in 2005.
Clients: Yellow Quill First Nation, Saskatoon Tribal Council, Health Canada, Indian and Northern Affairs Canada
Prime consultants: Associated Engineering (Dan Hogan, P.Eng., J.P. Mills, EIT) and WateResearch Corp., Saskatoon (Dr. Hans Peterson)
Geotechnical testing & plant foundations: P. Machibroda Engineering
Well exploration and development: Beckie Hydrogeologists
Contractor: Miner’s Construction with Ron’s Plbg.