Proactive blockage detection in sewer pipes using paired acoustic sensors: An experimental study

Sewer overflows due to blockages are significant challenges for water utilities worldwide, as these events pose substantial risks of disruption and contamination to society, the economy, and the environment. Accurately detecting blockages in sewer systems is essential to mitigate such incidents. This paper investigates the use of paired acoustic sensors in combination with a paired-impulse response function (paired-IRF) technique to detect, locate, and estimate sewer blockages, helping to prevent sewer overflow risks. Laboratory tests were conducted on both clean and blocked pipes with varying blockage types and severities. The acoustic responses of these pipes were analysed to distinguish between unobstructed and obstructed conditions. The paired IRF extracted was then applied to identify blockage locations and estimate blockage sizes. The presence of paired spikes in the paired-IRF trace serves as clear evidence of blockages within the tested sewer pipe, including those caused by tree root and solid materials. The technique accurately identified both the location and size of blockages, showing strong agreement with actual conditions observed during experiments. These findings express that the acoustic-based paired-IRF approach is a reliable method for blockage detection in sewer systems, enabling water utilities to take informed and timely actions before issues lead to environmental or public health impacts.