The methods used for clearing blockages in drainage pipes vary depending on the pipe diameter. For smaller pipes, those with diameters under 300mm, rodding is the typical method. This manual approach involves inserting meter-long rods into the pipe and physically maneuvering them to dislodge the blockage.
For pipes between 300mm and 700mm in diameter, water-jetting is often preferred. This method utilizes pressurized water from nearby fire hydrants to clear obstructions, providing a more powerful and efficient solution than manual rodding.
Winching, however, is a versatile method applicable to all pipe sizes. This technique involves using a winch to pull a cleaning tool through the pipe, effectively removing blockages over long distances. In fact, for pipes exceeding 1050mm in diameter, the Stormwater Drainage Manual specifies a maximum distance of 120m between manholes. This is because winching, with its 120m operational limit, is the primary maintenance method for such large pipes.
The maximum spacing of manholes for other pipe sizes is similarly determined based on their respective maintenance methods. This ensures that all sections of the drainage system are accessible for cleaning and repair, minimizing the risk of blockages and maintaining optimal performance.