Smart sewer sensors prevent wastewater overflows every day

Smart sensors deployed in Watercare’s wastewater network are preventing potentially major overflows on a daily basis, helping to protect public health and the environment.

Almost 5000 sensors have been rolled out in the past year as part of Watercare’s $12 million Smart Sewer Programme and are now preventing more than one overflow per day on average by detecting pipe blockages that can be cleared before they cause overflows.

Watercare smart systems manager David Moore says a recent example involved catching a blockage forming in the wastewater network in central Ellerslie ahead of a heavy rain event.

On Thursday 27 August, the sensors detected wastewater levels rising in a manhole.

“With an orange weather warning issued for heavy rain in the upcoming weekend, we moved quickly to investigate,” says Moore.

“The field crew found that the safety grill had become dislodged and fallen into another manhole in the network, where it was catching rags and debris and forming a blockage, causing wastewater to back up. The team removed the grill and flushed the local network before the weekend.

“The area was hit by heavy wet weather, and the sensors helped us prevent an overflow that would have impacted Ellerslie’s commercial centre, with the potential for properties to be flooded with wastewater.”

Another incident was averted when the sensors detected a blockage in a wastewater pipe in the central city, which would have caused an overflow outside the Commercial Bay complex.

Auckland deputy mayor Desley Simpson says every overflow prevented is a win for Auckland's communities, waterways and environment.

“Wastewater overflows can have significant consequences, including sewage backing up into homes and businesses, creating public health risks and contaminating local waterways. It's incredibly encouraging to see this technology helping Watercare identify and fix problems before they become serious incidents. This is a practical example of innovation delivering real benefits for Aucklanders every day while helping protect the places we value most.”

The Australian-made Kallipr radar level sensors are integrated with Northern Irish company StormHarvester's machine-learning analytics platform to convert network data into insights that Watercare can use to better understand and manage its wastewater network.

“Our immediate goal was fewer overflows through earlier blockage detection, and the sensors are delivering by preventing at least one blockage every day before it reaches properties or waterways,” says Moore.

“We are gathering enough data to see the patterns within the network that help us make more effective decisions about investigations, maintenance and investment.”

Watercare operates around 9000 kilometres of wastewater network serving 1.7 million people across Auckland.

The sensors were distributed across the network, especially in parts with issues like repeated blockages and groundwater intrusion into the wastewater pipes.

“With thousands of sensors reporting data, we can see how different parts of the network respond to weather conditions like rainfall. For example, a quick spike in flow levels that clears within hours points to water entering our pipes from private stormwater pipes being plumbed into our wastewater network, whereas a slow rise that doesn’t clear when the rain stops points to water getting in through cracks in the pipes that may need fixing,” says Moore.

“This kind of network-scale monitoring and analytics are helping us to prioritise maintenance, guide investigations, and support more targeted rehabilitation investment across the wastewater network.”