Civil Engineering - Waste Water Engineering - Discussion

Inverted siphons are used in sewer systems to carry flow under obstacles like rivers, roads, or valleys where the sewer cannot maintain a continuous downward slope.

They work under pressure, unlike gravity sewers, which typically flow at a slight slope.

Here’s how the three pipes work:

Low-Flow Pipe: Designed to handle low sewage flows efficiently. If a single large pipe were used during low flow periods, it could lead to issues such as sediment deposition because the velocity might not be enough to keep solids suspended. A smaller pipe ensures that flow velocities remain high enough to prevent blockages.

Intermediate-Flow Pipe: Used during normal or moderate flow conditions. This pipe is typically larger than the low-flow pipe and smaller than the high-flow pipe. It kicks in as flow increases beyond the capacity of the low-flow pipe.

High-Flow Pipe: This pipe is designed to handle peak flow conditions, such as during heavy rainfall or other high-demand situations. The pipe is the largest of the three and is activated only when the flow exceeds the capacity of the other two pipes.

The use of three pipes in an inverted siphon system ensures that the sewer can handle a wide range of flow conditions efficiently, minimizing the risk of blockages, sedimentation, and surcharging. Each pipe is typically fitted with flow control devices to manage which pipe carries the flow at any given time.

This setup is more reliable and flexible than a single or two-pipe system, which is why three pipes are commonly used in practice.

Thanks for giving the details @Rawal.