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Buried basins that collect runoff the streets and other ground surfaces, and are typically located below curb grates seen in the streets. They capture solid materials in the runoff and provide for the conveyance of the cleaner runoff through catchbasin leads (piping) to the sewer system.

Combined Sewer Overflow (CSO)
A mixture of wastewater and runoff found in combined sewers during rainfall or snowmelt events that spills to the environment untreated. CSOs enter the environment either directly or through a storm sewer, as the result of the capacities of the interceptor sewers and/or treatment plants being exceeded. There are 19 CSO locations in Edmonton's combined sewer system.

Combined Sewer System
A system of sewers designed to collect and convey wastewater and runoff from urban areas to the receiving stream or to a treatment plant if one is available. This is an old style of providing sewer service and drainage, and was discontinued in Edmonton the late 1950s in favour of separate storm and sanitary sewers.

The inadvertent connection of a sewer service or private drainage system to the incorrect public sewer system. For example, a sanitary sewer service from a house that discharges to the storm sewer in the street rather than the sanitary sewer.

Interceptor Sewer
A sewer designed to convey dry weather flow (and a minor component of wet weather flow) from the combined sewer system to the treatment plant. When wet weather flows exceed the capacity of the interceptor sewer, the excess flows are discharged to the environment as combined sewer overflow (CSO).

A location within the sewer systems where the flow may pass from one sewer system to another. Interconnections generally provide overflow relief to combined sewers in the event of sewer backup, thus minimizing basement flooding. These interconnections generally discharge excess flows to storm sewers and produce much smaller volumes than CSOs in Edmonton. There are 155 interconnections in Edmonton.

Roof Leader
The roof leader (or downspout) conveys runoff that has been collected in eavestroughs from roof tops, down to the ground surface or to a receiving sewer service.
Flows that run off the ground surface during rainfall or snowmelt events.

Sanitary Sewer System
A system of sewers designed to collect and convey household and industrial wastewater from urban areas to a wastewater treatment plant.

Storm Sewer System
A system of sewers designed to collect, store and convey runoff from urban areas to a receiving waterbody.

Stormwater Management
The management of runoff to provide controlled release rates to receiving systems, typically through the use of detention/retention facilities such as lakes.

Sump Pump
A sump (depression) and pump assembly that receives groundwater infiltration flows collected by weeping tiles located around the foundations of buildings, and pumps the flows up onto the outside ground surface.

A topographically defined area or region of land drained by a river/stream or system of rivers/streams such that all outflows are discharged through a single outlet.

Weeping Tile
A weeping tile (or foundation drain) is a perforated pipe that is located along the foundation of buildings to collect groundwater infiltration flows and route them to a sump pump for disposal on the surface, or a sewer service for disposal in a sewer.

For More Information

Drainage Infrastructure

General Information



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