What is the role of bypass pumping and when is it used?

Q:

What is the role of bypass pumping and when is it used?

A:

Aging sewer pipelines is a growing concern in many municipalities. This issue has led to an increase in activity aimed at rebuilding or rehabilitating current sewage infrastructure.

However, it is often necessary that existing sewer systems remain operational during ongoing construction activities. To achieve this, contractors rely heavily on bypass pumping systems during line repairs and sewer rehabilitation.

Bypass pumping involves using a system of pumps and pipelines to divert flows around existing infrastructure. The purpose of bypass pumping is to maintain uninterrupted service to customers while work is being performed on a section of the sewer line.

While this method is commonly used on sewer mains, it can also be used on other systems, such as water mains and pump stations.

The first step to bypass pumping is to cease flows in the vicinity of the work area. This is accomplished by using temporary plugs. These plugs are placed at upstream and downstream locations; thus, isolating the area in question.

The next step to bypass pumping involves setting up the pumps and bypass lines to reroute the incoming flows around the work zone. During this step, the length of the bypass line and the expected flow capacities must be known to ensure that the bypass pump is sized correctly.

Additionally, it is customary to have some redundancy in the pumping system to ensure that bypass flows can still be maintained in the event that one of the pumps fails. After work is completed, the pumps are removed, and the flow is restored to its original path.

While bypass pumping is necessary, one of its main drawbacks is that, in some situations, bypass lines may need to be routed above-ground. In this case, municipal corporations, residents, and other affected parties may need to be consulted prior to installation or rehabilitation works.

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Written by Krystal Nanan
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Krystal is a civil engineer and project manager with an MSc in Construction Engineering and Management. Her experience includes the project management of major infrastructure projects, construction supervision, and the design of various infrastructure elements including roadway, pavement, traffic safety elements and drainage.

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