Ask the experts Q&A: Wastewater
Atmos International
Leaders in leak detection, theft detection and simulation for pipelines
Martin Duff MIWater , Business Development Director for water and Harry Smith , Sales and Senior Research Engineer
Our experts take a deep dive into wastewater leakage
From rainwater and sewage to wet wipes, fats, oil and grease, wastewater pipelines carry a range of pollutants.
Leakage anywhere in the network has the potential to cause a pollution event that impacts the environment, public health and a utility’s reputation, so there needs to be a sense of urgency in finding leaks in a wastewater network.
We interviewed Business Development Director for water Martin Duff and Sales and Senior Research Engineer Harry Smith, who answered some of the key questions we get asked around wastewater, including:
What causes sewage pollution?
There are multiple causes of pollution. Blockages can occur in pipelines due to the buildup of things like wet wipes, fats, oils and grease, causing water to back up and exit the sewer into homes and the environment.
A common cause of sewage pollution is via combined sewer overflows (CSOs). CSOs are permitted to discharge into natural waterways during periods of high rainfall, when sewage treatment works are running at full capacity and can’t accept any more sewage. However, problems in the infrastructure can lead to CSOs spilling too early .
For example, pipelines that take treated final effluent from a sewage treatment works to be discharged into the sea can have leaks in them, causing them to fill up with sea water and creating a hydraulic back up in the system which causes the CSO to activate too early.
Rising sewer main bursts are another key area that cause pollution incidents. Rising sewer mains are pressurized pipelines carrying sewage uphill and are a notorious weak point on the wastewater network. They have a high rate of bursts and are often located near natural water resources and so can lead to damaging pollution incidents.
Learn more about the factors behind rising sewer mains failure, CSOs spilling prematurely and why early leak detection is the solution: Read our feature in Water Magazine
How is it possible to detect leaks on a rising sewer main?
We can detect leaks on a rising sewer main by utilizing the negative pressure wave method, which involves monitoring the pressure in the rising sewer main 60 times per second. A sudden drop in pressure may indicate a new leak.
This solution typically requires instrumentation at both ends of the rising sewer main, which can be challenging as it is difficult to access the top of a rising sewer main. However, we’re able to use the high point on the rising main to reflect the negative pressure wave back down the pipe so we can pick up both negative pressure waves with a single device.
Single ended leak detection allows us to both identify a new leak as it forms as well as estimate its location along the rising main.
Discover how we achieved this for a UK water utility: Download the project spotlight
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What are the key differences between clean water and wastewater applications when undertaking leak detection?
There is a cultural difference between leak detection in clean and wastewater networks.
In clean water networks, leakage is a byproduct associated with transporting water under pressure to customers. However, reducing leakage has been a regulatory obligation in the UK for over 25 years, so leak detection is a mature concept in clean water applications.
The techniques and technologies used in clean water networks revolve around finding existing leaks, typically using acoustic techniques or external methods, but this can be a time-consuming exercise.
In wastewater applications leak detection doesn’t really exist, possibly due to the network mostly not being pressurized. Where there is positive pressure such as rising sewer mains, there are minimal access points to install leak detection equipment.
However, there needs to be a sense of urgency in finding wastewater leaks due to the environmental consequences they can have. This is the approach taken in the oil and gas industry, which has a very mature leak detection approach focused on finding new leaks as they form. Atmos is using its 30 years’ experience in the oil and gas industry to help adapt leak detection technologies that can be used in the wastewater network.
How could a leak detection system be used on an intermittent pumped rising main?
We have lots of experience in the oil industry of intermittent pump activities. In wastewater networks most of the network is gravity fed, but there are intermittently pumped sections of pipeline known as rising sewer mains.
Our Atmos Wave technology (negative pressure wave) works in pressurized pipelines, including rising sewer mains which have a high rate of failure compared to the gravity fed part of the network.
Our technology understands the difference between pumps operating and bursts occurring, so an intermittently pumped rising main is within the technology’s capability. High pump noise can potentially impact the system performance, but we have a set of algorithms to manage that.
If we know where the high point is at the end of the rising sewer main we can monitor the rising main with just one instrument at the bottom of the main, as any leaks that occur along it can be reflected off the high point to provide a leak location.
How can Atmos' technology help water utilities?
Atmos is using its 30 years’ experience in the oil and gas industry to help adapt leak detection technologies that can be used in the wastewater network to overcome the following challenges and more:
Read our full Ask the experts (wastewater) article here or watch the video .