What are sewer overflows and plant bypasses?
A sewer system overflow occurs when sanitary sewers are overwhelmed by storm water inflow and infiltration during wet weather events. Sewage mixed with storm water discharges directly into local waterways through an outlet to assist in the prevention of basement flooding.
A wastewater treatment plant bypass occurs when flow exceeds capacity of the treatment plant. The raw sewage and storm water discharge directly into local waterways through an outlet to assist in preventing basement flooding. The wastewater treatment plant treats as much sewage as possible prior to any plant bypass by directing a portion of the flow to receive primary treatment but it bypasses secondary treatment.
What is the issue?
Sewer overflows in London discharge untreated sewage directly into the Thames River. Plant bypasses also directly discharge untreated sewage and secondary bypasses discharge partially treated sewage to prevent basement flooding.
Weeping tile connections, roof drainage connections and infiltration discharging into a homeowner’s sanitary sewer line during a major rain or thaw event can cause the main sewer line to overflow.
What can be done?
To reduce overflow and bypass issues reduction of weeping tile drains to the sanitary sewer is required.
Weeping tile connections to the sanitary sewer occur in about 48% of the homes in London. The City has undertaken the Sherwood Forest Weeping Tile Disconnect Project – a pilot program designed to reduce the risk of basement flooding by disconnecting foundation drains from the sanitary sewer system and installing backwater valves for homes on Blanchard Crescent.
Work is planned to provide primary treatment (partial treatment) to the peak flows during snow melt and rain events. This does not solve the problem, but reduces the impact of rain getting into our sanitary sewers.
How can you help?
If you are concerned with the problem of basement flooding and raw or partially treated sewage being released into the Thames River, you can be a part of the solution!
If your weeping tile is connected to the sanitary sewer inside your home, you can have your weeping tiles disconnected from the sanitary sewer and reconnected to the City’s storm water system.
The City has the Basement Flooding Grant Program in place to assist homeowners with the cost.
We need your help London!