Road collapsed due to sewer failure

Your sewer network maintenance business case in 1 minute!

Your sewer network maintenance business case in 1 minute!

Are you having trouble getting approval for a routine inspection program for your sewer network? Here is some information to bolster your business case.

The Challenge

Councils and utilities are rarely in a position to inspect 100% of their sewer or stormwater networks. This means that careful selection is required when planning which pipes, manholes, and pits to inspect. This should involve risk-based decisions that often include a focus on high consequence of failure locations. However, risk is a combination of both consequence and likelihood of failure. For sewer networks, there is often a significantly increased likelihood of failure immediately downstream of sewer rising mains (pumped mains) due to sulphuric acid generation

What causes hydrogen sulphide corrosion in sewers?

Sulphate in sewage is converted to hydrogen sulphide (H2S) by bacteria present in the sediment/biofilm layer. The H2S can move from the liquid to gas phase which is often the cause of customer odour complaints. Sulphur oxidising bacteria (SOB) above the water level convert this gas to sulphuric acid which can be highly corrosive to the surface of concrete manholes and pipes.

Why are inspections necessary?

The cost and the associated impact of a partial or full failure of these assets can be significant. Understanding where these issues are likely to occur, the current condition of these assets, and the rate of condition change over time allows better management of risk and can save large reactive repair expenses.

What can I do about managing these assets?

Periodic inspection of the first few manholes downstream of rising main outlets and the receiving gravity pipework (especially if concrete/asbestos cement) is a prudent investment and recommended as a subset of your broader condition inspection programming. The image above is an example of proactive rehabilitation of two manholes just downstream of a rising main. This planned work is a fraction of the cost of dealing with a reactive repair after failure.

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AI in Sewer

AI in Sewers

AI in Sewers

The importance of the pipe network beneath out feet

Our cities and suburbs are supported by a vast underground network of water, wastewater and storm water infrastructure. This network of gravity pipes, pumps and filtration systems play a very important role in the quality of our life, eliminating disease, safeguarding the environment, and protecting communities.

However, parts of this aging infrastructure are nearing the end of its useful life and now (more than ever) requires closer attention. Without attention, this situation is not sustainable.

Most of our water and wastewater infrastructure were installed during the 19th century and municipalities are facing the challenge of broad-scale infrastructure replacements or repairs costing hundreds of millions of dollars.

Adding to all this is the changing climate factor, meaning systems that were designed 30 or so years ago may not be sufficient to support everchanging environment around it.

To extend the life of infrastructure, reliance on smart city technology capabilities is critical. By creating visibility into buried assets to understand the conditions of underground infrastructure, utilities can compare current performance with expectations, and predict when and where problems may arise. This also leads the way to prioritisation of maintenance work, decreasing downtime of the assets, resulting in reduced interruptions.

Today’s technology

With sensors and actuators becoming more cost effective, an array of technologies is becoming available for the pipe industry. For pressure pipes or pipes transporting materials under high pressure, static sensors are being used to help monitor the health of the asset. In sewer and stormwater applications, inspection by video still is widely adopted with assessment being carried out visually by an expert.

With operational technology (OT) and information technology (IT) coming together, data that were once only available in isolated networks is now available via the world wide web. What this means is CCTV operators are no longer needing to download inspection videos to a hard-drive in order to assess the condition of the pipe in the office, instead they can upload the video file over the cloud.

AI at your service

With more data being available and accessible, a path has been paved for advanced technology such as artificial intelligence or AI. These smart algorithms feed on data, in-fact, the more data that is available, the quicker and more accurate an AI system can become.

Like other technologies, AI is tool to better understand a problem so to make data driven decisions. One of the areas where AI is helping the pipe industry is in the field of video processing. The traditional means of CCTV condition assessment presents several challenges including time taken to review the videos and identify defects, the operator subjectivity and field conditions making visual inspections difficult.

The AI models are pre-trained to detect certain anomalies, in this case pipe features and defects. The inspection video is then ingested and inferenced against the trained model. The result is the identification of the type and importance of anomalies.

VAPAR’s AI

Integrating the above-mentioned technologies, the VAPAR.Solutions platform leverages cloud computing and its AI engine to automatically assess inspection videos that users upload. The platform is accessed via any web browser where videos can be uploaded, analysed, manually audited by an expert (if required), with a report generated and stored, eliminating the need for hard drives to back up the video data and corresponding reports.

With this approach, both asset owners and CCTV contractors are reducing the time taken for assessments, standardising the process to remove any subjectivity and utilising AI to deep dive into the data to get better outcomes.

In 2020, VAPAR worked with asset owners in Victoria, Australia, where the results showed that the solution outperformed the same inspection carried out manually. The AI algorithm missed fewer defects and was more accurate in grading the pipes. To date, VAPAR has processed over 3 million images, which means the AI has only become quicker and more accurate.

Industry impact

With the need for the pipe network needing special attention, technology is adding another lens to take a closer look. It’s empowering engineers, operators, and decision-makers to make data driven decisions more cost effectively and proficiently.

sewer overflow

Why do sewers get blocked?

Why do sewers get blocked?


Dry weather sewer overflows caused by blockages can create significant issues for utility providers, the community, and the environment. What are some of the reasons sewer/wastewater pipes become blocked?

Tree roots

The number one cause of sewer blockages in most networks is tree roots.1 In addition to sunlight and carbon dioxide, trees require water and nutrients to grow and survive. The consistent flow through sewer pipes provides a rich and attractive source for trees. While the gravity pipe network would ideally be a closed system, there are numerous pipe joints and cracks where tree roots are able to squeeze through as they seek out nutrients. If enough of a gap exists, the root mass can become so large within the pipe that it can eventually block, causing a back-up of sewage flow and discharge at a point upstream. The point of discharge is commonly a sewer maintenance hole or house overflow relief gully. Dry weather overflows may persist for some time before being observed and reported for fixing.

FOG: fats, oils and grease

Another contributor to sewer blockages is FOG: fats, oils and grease. If you’ve ever wondered why you are asked not to pour these cooking by-products down the sink, this is the reason. Incorrectly managed trade waste from food establishments is also a significant contributor to FOG issues in a sewer network. These products increase the likelihood of a blocked sewer and overflow. Fats, oils, and grease can solidify after they cool and build-up on the inside of pipe walls, they have a tendency to coagulate with similar particles, or exacerbate already existing root intrusion issues, and can result in partial or complete blockage of a pipe. An internet search of ‘sewer fatbergs’ will provide graphical insight into the scale of the problem.

Foreign objects

A third cause of sewer overflows is the flushing of objects down the toilet that belong in the rubbish bin. The most recent offender on this list is wet wipes. While toilet paper is biodegradable and designed to break apart after flushing, wet wipes are not the same. This material interacts with both tree roots, fat deposits and other solid materials dramatically increasing the likelihood of blockages. Other common items that don’t belong in the sewer system and contribute to blockages include paper towels, sanitary items, condoms, hair, kitty litter, and cotton balls.

Other potential triggers for blockages in pipes are the build-up of sediment or broken pieces of pipe which reduce the cross-sectional area of a pipe and can lead to partial chokes and eventual blockage.

How are these defects identified during a CCTV inspection?

VAPAR uses artificial intelligence to automatically identify and categorise pipe defects including root intrusion, debris/deposits (incl. FOG build-up), and other obstructions within a pipe that can identify the potential risk of blockage. The VAPAR.Solutions platform provides defect level reporting that can be matched with historical work orders and blockage events to assist in pipe maintenance programs to reduce the risk of future blockages.

  1. Sewer performance reporting: Factors that influence blockages (Marlow et al., 2011)