Sewer systems play a vital role in our society as they work to drain away the waste generated in our domestic and commercial buildings. Vacuum, gravity and pressure are the three most common types of major sewage systems, each of which operates differently and is installed differently.
What is a sewer main?
The main sewer is a sewage system’s major conduit that runs beneath public streets and collects wastewater from lateral connections. These lateral pipelines are smaller pipelines connecting homes and businesses to the main sewer line. The sewage from these branches is carried by the main sewer to a sewage treatment facility, where it is processed before being safely discharged.
What is a sewer network?
A sewage system’s most fundamental component is the sewer network. A sewer network is a system of pipes and sewers that collect and transport wastewater from urban and industrial areas to treatment facilities. This can be accomplished by gravity flow or the use of pumping stations when gravity flow is not possible. Ground conditions, topography, effluent composition and construction sequencing all have an impact on the development of a sewer network and which system is used.
What is a gravity sewer system?
Gravity sewers are underground piping systems that are sloped downward from the source towards the destination. There are no pumps or pressurised components in the system, therefore the waste that runs through the pipes is geared by gravity. Although pressurised systems are becoming more widespread, most sewage and stormwater sewer systems were originally constructed as gravity sewers.
To prevent airlocks in the system, gravity sewers are designed in such a way so that the product does not fill the pipe. However, the product flow through the pipes may grow beyond design as pipes age and water ingress occurs through fractures, which can result in inflow problems. Since there are no pumps, accompanying filters or blades to break up and remove materials, gravity sewers are also susceptible to clogs.
What is a pressure sewage system?
A pressure sewage system is a centralised sewage system that uses small, low-powered grinder pumps in each property and connects them to a centralised discharge network. Due to the pressure created at each property connection, the sewage is moved to a treatment facility or another connecting sewer system.
The network is made up of small-diameter poly tubing that is put into narrow and shallow trenches or drilled in a certain direction. This allows the network to be developed with less emphasis on the slope and greater flexibility over the design of the network. Pressure sewage systems are particularly common in rocky and steep places where gravity sewer infrastructure would be expensive.
What is a vacuum sewage system?
Vacuum sewerage systems are utilised for a variety of reasons, but they’re most commonly used when ground conditions make a standard gravity system impractical to build or if there’s a concern about the environment. A vacuum sewerage system uses differential air pressure and gravity to carry sewage quickly from collection pits to a central collection tank and then to a point of discharge through a network.
AWD Civil are the experts in civil engineering projects, managing and planning many projects in Queensland and New South Wales. If you have a project that we can assist in, contact our team at 07 3200 5766.