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by Annabelle Powell, Journalist, Utility magazine

Dams play a critical role in securing our water supply, so it’s vital that issues such as seepage – which threaten their integrity – are detected as early as possible. Here, Utility explores how Hunter Water has employed innovative satellite technology to increase the accuracy of its dam monitoring.

Hunter Water has implemented cutting-edge satellite technology to monitor Grahamstown Dam and Chichester Dam, its two biggest assets. The state-of-the-art safety upgrade has engaged Australian company Detection Services, in partnership with United Kingdom-based analytics experts Rezatec.

The three-year programs at the two dams will use Rezatec’s Geospatial Artificial Intelligence (AI), increasing the frequency and accuracy of monitoring, while also reducing inspection costs and risks to employees and contractors.

Geospatial Satellite AI technology

Hunter Water’s journey into using geospatial satellite AI technology began when it was looking at ways to implement a movement monitoring system at Grahamstown Dam. Grahamstown faced unique challenges, with 5km of embankment and a public road along its crest with an 80km per hour speed limit.

These factors meant that setting up a traditional survey network on the dam would be difficult and even then, would only monitor select points.

Hunter Water began working on technology that would provide greater coverage of the dam itself and produce frequent, accurate information.

This led it to investigate satellite monitoring. Satellite-based technology measures interference patterns with radio signals that are emitted from a satellite. Every time the satellite passes over the top of the dam, it measures the difference in the reflected pattern and can translate it into a movement.

Hunter Water Dam Safety Engineer, Daniel Turnbull, said using this advanced technology was a game- changer for the utility on several levels.

“We receive high-quality data showing any changes on a very fine scale, which gives us increased confidence in our dams’ integrity and
allows us to proactively manage the assets,” Mr Turnbull said. “Satellite monitoring minimises the fieldwork required, reducing the exposure of our people to potential hazards.”

Unparalleled accuracy

Mr Turnbull said Hunter Water had trialled other technologies such as drones but the accuracy that they were able to achieve was only in the 20 to 30 millimeter range. “The accuracy quoted by the satellite monitoring is in the one to two millimetre range,” Mr Turnbull said.

“For dams, being able to detect movement of one to two millimetres is hugely significant.” The dam monitoring solution features an online portal offering a dashboard view, while detailed reports provide early information and analysis of any potentially irregular ground movement and vegetation growth.

Mr Turnbull said the technology has so far not detected any issues, which is a good sign for the dams. “We like to see that there’s very little movement and we’re not seeing any abnormal readings,” Mr Turnbull said.

“Because there’s so much data that we receive, we find that we may get some anomalies that show up and we can send our site staff out to inspect in more detail to see if it is an issue.

“But every time that has occurred, the subsequent batch of data provided by the satellite monitoring has revealed that it was an anomaly and not an actual issue at the dam.”

Chichester dam

A baseline for comparison

Mr Turnbull said as the baseline project for Grahamstown Dam was done in the middle of a drought, the ground and embankments were at their driest in at least a decade.

“We’ve gone from one of the driest periods that we’ve had in a long time, now into one of the wetter periods,” Mr Turnbull said. “Having covered that range, it sets a really good baseline and thresholds for us, so we can see if the moisture’s going above or below those and provides us with a really good comparison.”

Future applications of satellite technology

Rezatec first began monitoring Grahamstown Dam on a trial basis in 2021, and with the pilot deemed a success, Chichester Dam joined the program. Over time, Hunter Water will look to apply Geospatial AI technology to other areas across its network.

“We’ve basically got both of our water supply dams covered at the moment, but the satellite monitoring also has applications along the lines of checking for leakage on pipelines,” Mr Turnbull said.

“So we’ve been thinking about whether we could use that along some of our major trunk water mains that run through isolated locations where we don’t have a lot of people out there to inspect. “It might provide early warning that we are getting some leakage in those areas.

And the other facet that we’re starting to look at is whether it can be utilized to monitor for algal blooms on our dam storages as well.”

Mr Turnbull said the biggest benefit of the project is the peace of mind made possible by the increased coverage of the dams and frequency of information. “The regulations for dam safety require us to, depending on the dam, either undertake an annual or a two yearly survey of the dam, whereas using the satellite monitoring, we’re getting monthly updates of the data,” Mr Turnbull said.

“Every month, the satellite makes a couple of cycles overhead. So the satellites are passing over roughly every 12 or 13 days. “To get that volume of information, we know that we’re checking our dam more frequently and we’re likely to detect any emerging issues faster.”

Mr Turnbull said the project is in a great position as the data being produced is as expected. “It’s boring data if you are looking for changes, but really reassuring for a dam owner,” Mr Turnbull said.

©2022 Utility Magazine. All rights reserved

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