Utility Services has implemented a long-term CSO Control Plan to reduce the impact to the ecosystem. It comprises Early Action Control Plan (commenced in 2001) and Long Term Control Plan (commenced in 2005). These plans include improvements to sewer infrastructure (pipes, weirs, and storage facilities), and processes.
Costs will be passed on to Edmonton businesses and homeowners through regular monthly utility charges. The main benefit is a decrease of up to 30% average annually in the amount of sewer water that reaches the river from CSOs, resulting in cleaner water and a healthier ecosystem.
The CSO Control Strategy will be updated every ten years to determine its success and confirm its direction.
Early Action Control Plan
- In-line System Storage: Moveable gates and time controlled operating system to cope with excess flow and provide added storage time. There has been two such gates in operation.
- Solids and Floatables Control: Efforts will be made to control the amount of solids and floatables discharged from CSOs.
- On-Lot Sewer Separation Initiative: As opportunities arise, projects will be undertaken to divert surface runoff away from the combined sewer system, such as roof leader and catchbasin disconnections.
- Operation and Maintenance: Improving documentation, staff training, and annual reviews of system operation and maintenance procedures.
- Monitoring Network Upgrades: Expansion of the current monitoring program to monitor additional parameters which affect water quality.
- Wet Weather Flow Management Plan: Study and development of strategies to deal with excess flows (wet weather flows) reaching the Gold Bar Wastewater Treatment Plant.
Long Term Control Plan
- Gold Bar Wastewater Treatment Plant: Increase plant capacity for wet weather excess flow to 1,200 MLD to current primary treatment storage.
- Sewer Tunnel Construction: New tunnels at Rat Creek and Highlands CSO sites will increase the flow that reaches the plant during wet weather conditions.
- Weir Modification: Weirs (overflow dams in the sewers) at 4 locations will be modified to contain more flow in the sewers, reducing the frequency and volume of overflow at those sites.
- Strathearn Storage: Underground storage near 98 Avenue and 85 Street will capture CSO flows to reduce the frequency and volume of overflow at the site.
- Opportunistic Sewer Separation: This involves upgrading or converting combined sewer systems into separate sanitary sewers and storm sewers as opportunities arise. Opportunities arise when the infrastructure (roads, buried utilities, and etc.) in older neighbourhoods are rehabilitated as part of ongoing neighbourhood renewal programs in Edmonton.