Technologies to Assess Condition of Wastewater Rising Mains

This paper discusses the application and limitations of industry leading technologies used to assess the condition of wastewater rising mains. These technologies include destructive technologies (DT) as well as non-destructive technologies (NDT).

Wastewater rising mains are an integral component of the wastewater network. However, they often have no redundancy with a pump station being served by only one rising main. Failures to these critical assets occur in our cities and have the potential to impact the quality of the environment, jeopardize the health of our communities, and cause financial pain by damaging property and requiring costly unplanned repairs. Understanding the condition of these critical assets is paramount to ensure service and performance reliability. It is also necessary to understand the condition of these assets as they age and become vulnerable to failure.

Wastewater rising mains are difficult to properly inspect, as they are under pressure and cannot usually be taken out of service. Faults that cause problems may be very small and are often not possible to identify from the more common inspections that are carried out.

A variety of materials are used for wastewater rising mains. These materials perform differently depending on the application, service conditions, installation, age, and manufacturer. This adds to the complexity of finding the appropriate technology to assess the condition of the wastewater rising main.

Technologies are available to inspect wastewater rising mains which typically involve DT as well as NDT means. However, the application and limitation of these technologies is not well established.

This paper presents a review of available condition assessment technologies for wastewater rising mains. Consideration is given to vulnerability issues with certain materials and particular service conditions. The knowledge gained in the proper application of technology currently available ensures the highest level of confidence as to the condition of the wastewater rising mains. Ultimately, this knowledge informs the owner of a wastewater rising main’s vulnerability, remaining operational life, and provides information needed to effectively plan for renewal of the asset.

This paper describes the process undertaken to survey and apply available technology. The process included the initial compiling, validating and understanding the wastewater rising main system, its characteristics and vulnerability. Options for DT and NDT technologies were considered. Subsequently, a condition assessment programme will be developed to determine condition grade and estimated remaining operational life for each asset.