The Intelligent Water Networks’ Remote Technologies Program recently conducted a series of trials designed to investigate, test and evaluate the benefits of using a Remotely Operated Vehicle (ROV) to clean undrained water tanks.
Potable water tanks require regular cleaning so that a high level of water quality is maintained, however current methods for cleaning online tanks have inherent safety risks.
“At present, tanks are taken offline and drained, or divers are sent in to clean the tanks manually while the tanks aren’t in operation,” Project Manager Tanya Pearson said.
“Using divers to clean sediment build-up is costly, labour-intensive and raises hazard exposure safety concerns, so our project looked at ROVs as an alternative in order to eliminate the need for confined space entry by humans. We also assessed the technology’s efficiency and cost in comparison to manual cleaning,” Ms Pearson said.
In October of this year, Kelly’s Australia was commissioned to trial the WEDA VR-600 underwater cleaning ROV supplied by VoR Environmental at six Victorian water corporation sites: Yarra Valley Water, Coliban Water, South East Water, Goulburn Valley Water, Westernport Water and East Gippsland Water.
Not unlike a pool cleaner, the ROV tank cleaner crawls along the bottom of a water tank or basin on caterpillar tracks. It uses rotating brushes to loosen stubborn material and a powerful submersible pump to suck up sediment. The waste is discharged via a hose into nearby sewers or a tanker truck, or where appropriate, disposed into the stormwater system. The ROV is also equipped with lights and cameras, is steered by an operator using real-time video, and cleans between 80 and 90 square metres per hour.
The WEDA VR-600 ROV was trialled on five water tanks and one basin, some of which remained online and some of which were taken offline.
Upon completion of the trials, data revealed that the ROV effectively and efficiently cleaned the base of the water tanks, and the technology’s operational cost was found to be comparable to that of using divers. The ROV also eliminated the need for confined space entry by humans thereby cancelling out its associated risk factors. Turbidity monitoring at the tank outlets and CCTV vision also confirmed that ROVs are capable of cleaning tanks whilst they’re in service, and can do so without disturbing sediments or causing slugs of dirty water to reach the outlet. Unfortunately, the ROV was unable to clean the basin at East Gippsland Water, due to the uneven nature of the basin’s surface, and its sloping sides.
Project Manager Tanya Pearson was pleased with the outcomes of the various trials.
“IWN’s ROV Tank Cleaning Project has provided the water industry with some extremely valuable learnings.”