Drones enter sewers no human can reach

In a first for the UK, drones and lasers are being used together to improve Scotland’s sewers, reaching parts of the network humans cannot reach.

A combination of drones and laser technology adapted for use in the wastewater industry is being deployed by Scottish Water to survey its network of more than 53,000km of Victorian sewers.

The drone and light detection & ranging (LiDAR) technology will scan parts of the network that traditional surveying methods cannot access, enabling the public utility to more accurately assess the sewers’ condition.

The move will reduce the risk of sewer leaks, collapses and pollution, and at the same time reduce carbon emissions from network surveys by as much as 80 per cent. This is because fewer workers are now needed to access the sewers for surveying, cutting the number of vehicles on the road.

The project is a collaboration between Caledonia Water Alliance (CWA), civil engineering trenchless specialist Environmental Techniques and drone manufacturer Good Friday Robotics.

“We want to improve the accuracy of our surveys and, for safety reasons, reduce the number of workers needed to carry out work inside sewers. The drone does both and will also help us reach net zero carbon emissions."

Iain Jones, Scottish Water

Iain Jones, risk and lifecycle planning manager at Scottish Water, said: “This is the first time we’ve used drones adapted for sewers and LiDAR together for sewer surveys and we are really excited about it.

“We want to improve the accuracy of our surveys and, for safety reasons, we want to reduce the number of workers needed to carry out survey work inside sewers. The drone does both and they will also help us in our aim to reach net zero carbon emissions by 2040.

“Factors such as depth, flows and debris can significantly slow down a worker entry survey in a way that does not affect the drones. Because of the reduction in the number of workers involved, a large number of site vans and vehicle deliveries are not required and so carbon emissions are reduced.”

LiDAR is a laser scanning tool that measures distances and the associated software creates an accurate computerised 3D point field output which can be viewed on-screen. The drone carries the LiDAR and camera onboard as it flies inside the pipe to identify issues such as cracks, holes, partial collapses, infiltration and root ingress.

Image: Scottish Water

A worker controls or pilots the drone as it flies along the pipe and uses video for visual inspection and LiDAR for measurement. The outputs are then manually reviewed by operators to spot and code the defects, with the kit providing substantially better video quality, defect confirmation and location accuracy than traditional techniques.

Specifically adapted for sewers, the drones are made of carbon fibre to reduce their weight and extend battery life. The adapted technology was used together for the first time on a large brick sewer in Bath Street in Glasgow city centre in July and is set to be rolled out and used at other locations in Glasgow, Edinburgh, Aberdeen and some rural areas.

Image: Scottish Water