Sewer Design



The design of a gravity sewer can be a rather sophisticated task. There are many factors that need to be considered such as the variation of sewage flow between dry and wet season. In the latter, stormwater runoff is often included in the flow. It is important to note that sewer drainage and stormwater drainage are not the same.


What is Involved in Sewer Design?

Adequate sewer design often varies between authorities and areas. Usually, sewage flow is required to be separate from the stormwater flow. However, there is the occasional overflow of stormwater onto the sewer drainage during the wet season.

Sewer design takes into account the normal average sewage flow (for wet and dry season) - this determines the sewer pipe size. The design must meet strict self-cleansing criteria under dry weather condition.


What Happens to Sewage After it Leaves the System?

Sewage is usually directed towards a water treatment facility. The sewage is then treated and becomes wastewater. The wastewater is then discharged, either in coastal areas, or rerouted back into the water system to be reused, depending on the water quality. Trade wastewater, i.e. wastewater that originates from the industry, requires separate water treatment.


Why Neilly Davies for Sewer design?

Neilly Davies hydraulic engineers have over 35 years experience in sewer design and extensions for residential, commercial and industrial projects.

No matter your project scale or complexity, our engineers will handle all the required paperwork including liaising with local and state government authorities to provide you with a compliant design that is buildable and cost-effective.


For more information about our sewer design services or to discuss your project in more detail, call us now 1300 730 340.

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