Hong Kong is faced with problems of dense population, scarce land and heavy traffic flow; complex utility's pipe networks are usually installed underground, thus extra safety concern and expertise are specially required before carrying out clean-up.

The cleaning of box-type storm water drains has always been considered as a project of high technical expertise: the underground drains are often silted up by sand and debris, and are possibly to produce poisonous or even flammable gases due to decaying substances. Conventional way requires workers to go inside clean manually within confined spaces and water, but such method is not effective and efficient when removing a large quantity of the cleaned sediments from the enclosed area. The excavated sediments, would release odor under exposure and cause nuisance to the public. Clean-up work will become even more challenging if the drains locates in the tidal zone because the drains would be long inundated by the extremely high flow of sea currents, and the water level would change unpredictably with tidal fluctuations.