A novel method for rapid inspection of sewer networks: combining acoustic and optical means

Operation and maintenance of the public sewer system represent key tasks for an operator. Condition assessment is usually conducted by conventional closed circuit television (CCTV) inspection. However, alternative tools such as manhole-zoom cameras (MZCs) and the acoustic technology SewerBatt® are available today. The INNOKANIS project investigates structural and operational condition assessment in the sewer system by means of 3 MZC models and SewerBatt® to develop a combined optical and acoustic device as cost-effective alternative to conventional CCTV inspection. The first field trials of the ongoing project were conducted in Austria in 2011. 640 conditions according to EN 13508-2/A1 were investigated and compared against conventional CCTV reports. Individual and combined detection rates for both devices were calculated. Based on the current findings, both MZC and SewerBatt® are effective alternatives to conventional CCTV inspection. In addition, performance is significantly enhanced when both devices are used in combination.