Sewer system

A sewer system comprises a network of pipelines that collect and transport waste- and stormwater to a wastewater treatment plant or the receiving waters.

A sewer system comprises a network of pipelines and technical installations (e.g. pumping stations). The system collects and transports waste- and stormwater from more than one source to a wastewater treatment plant or the receiving waters.

The sewer system can be either a combined or separate sewer system. The combined sewer system transports both sanitary wastewater (liquid and waterborne wastes from residences, commercial buildings, industrial complexes etc.) and surface/stormwater in the same pipeline. The separate sewer transports wastewater in a separate sanitary sewer pipeline and stormwater in another pipeline called the storm sewer.

The branched sewer network is divided into smaller units termed lateral, collector, trunk and intercepting sewer:

1) Lateral Sewer
A conduit that receives sewage or stormwater from residential, commercial or industrial structures and discharges into a public collector sewer.

2) Collector Sewer
A conduit that receives sewage or stormwater from two or more lateral sewers or other branch conduits.

3) Trunk Sewer
A principal sewer which collects the flow from two or more collector sewers.

4) Intercepting Sewer
A sewer that receives sewage from a number of collector and trunk separate sewers and specific, limited/controlled quantities of wastewater from combination sewers through diversion structures and conveys that wastewater to a point for treatment or disposal.

Through the sewer system the wastewater can either be transported by gravity or by pumping:

Gravity main
Flow is caused by the force of gravity and the pipeline is designed usually to operate partially full.

Rising main
A pipeline from a pumping station through which a liquid is transported under pressure. A rising main is used to transport sewage where gravity flow is not possible or practical.





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