Sewer sensors examine the parts the inspectors cannot reach

A remote control sensing device is being developed to detect defects in sewer walls.

Using both ultrasound and laser light, digital information on the condition of the sewer walls is fed back to a computer which can be programmed to spot problems.

The research is being carried out by a team in the Department of Mechanical Engineering at King’s College London, led by Dr Kaspar Althoefer and Professor Lakmal Seneviratne. Funding is from the Swindon based Engineering and Physical Sciences Research Council.

It is estimated that some 20 percent of the UK’s ageing sewage network is damaged in some way, leading to collapses and blockages. Many of the sewers are also too small for inspectors to get to, remote video cameras can be used but they cannot see through water and the recorded video images do not always pick up all the cracks.

The King’s team uses an ultrasound sensor to scan the area of pipe, which is below any water. “This can pick up evidence of cracks, or roots growing into the pipe, and relay it back to the base station” says Dr Althoefer. They are also using a laser system in conjunction with the video camera. Defects are indicated by changes in the laser pattern projected on to the walls.

Eventually, completely autonomous sensing machines could spend long periods in the sewer network, roaming the pipes and collecting essential information about their condition. The data could then be retrieved at regular intervals to allow engineers to improve their strategies for the repair and maintenance of the pipe network, which is vital to ensure it continues to function effectively.