The Town of Edson's water supply comes from a well system. Currently we have 11 wells, with 9 of them actively supplying water.
The water is treated before entering the potable system. A 12% sodium hypochlorite liquid solution is used, along with disinfection piping, to achieve a 4-log virus removal rate.
Some of the advantages of a well system:
wells are are considered high quality and require minimal treatment to meet Canadian drinking water guidelines
maintenance costs are low
more than one well source
economical building costs
wells are located close to existing distribution lines.
Some disadvantages are supply volumes are lower compared to a river, wells are spread out around the Town, there are multiple pumps and buildings to maintain, and wells require constant exploration.
While we do draw water from the aquifer, the environmental benefits to a well system are the reduction in chemicals for treatment and a reduction in power consumption compared to traditional treatment facilities along the river.
Edson's new Wastewater Treatment Plant (WWTP) came online in 2019. This facility was required following some testing and regulatory changes.
The new WWTP includes:
Pumping capacity for up to 32 million liters of wastewater per day.
Primary screens and wash press to remove rags, large rocks, and other plastic debris from the waste stream.
Grit removal system.
Two combined treatment units, allowing one to be taken out of service for cleaning.
Some key benefits of the new WWTP:
Ammonia was reduced from levels as high as 35 mg/L in 2009/2010 study to continuously below 5 mg/L under the new operating approval.
Effluent pH on average has been reduced.
Town of Edson has been passing its LC50 testing, which is a direct measure of impact to aquatic life.
The WWTP also comes with some additional ongoing costs to the Town of Edson through regular ground monitoring and performance assessments. This is estimated at about $850,000 for 2020.
In 2012, the Town of Edson completed a study to look at impacts from the existing lagoon system on the McLeod River. The study was requested by Alberta Environment and Parks as part of a program to determine whether municipalities could achieve national minimum performance standards. The study examined wastewater parameters, river data, and studied the impacts of effluent on aquatic life over several years. The final study indicated that upgrades would have to be implemented in order to comply with the new performance standards, particularly to reduce the concentration of unionized ammonia being discharged from the treatment facility.
Design and construction of the upgrades took several years to complete. Design included effluent monitoring, process modelling, equipment layout, and many discussions with regulators prior to construction.
The design of the new facility allows further expansion of the facility to treat additional wastewater from residents, reduce certain chemical parameters, and include effluent disinfection in the future as our operating approval limits change.