Method for clearing underground drainage duct with remote control seals at the bottom of a vertical shaft to provide a head of water to flush into the duct

摘要

A method for flushing an underground drainage duct, or sewer, has one or more vertical shafts (2) between surface grids/covers (3) and to top of the drain (1). A remote control sealing system is fitted near to the bottom of the vertical shaft to close and build up a head of water which is rapidly release, by remote control, to flush into the drain and remove any blockages, sediment etc. The remote control seal can be an inflated airbag (9) on a tilting mounting (8), a flap valve or any other suitable valve system.