Solid transport in building drainage networks
An essential requirement of building drainage networks is that waste solids are transported to a collection drain or sewer connection without undue deposition leading to maintenance issues and possible health hazards. It is inevitable that deposition will occur; however under satisfactory operating conditions such deposits are moved on by later appliance discharges or joining flows. It is essential therefore to develop a sound understanding of the parameters affecting and governing solid transport, deposition and subsequent motion. This requires a consideration of the properties of the network, in terms of the expected parameters of diameter, roughness, slope and length to the next flow confluence. In addition it is necessary to consider the frequency and type of appliance discharge to the network and the presence of any flow-enhancing devices. It is also essential to understand the mechanism of waste introduction to the network through the discharge profiles of any w.c. appliances served by the system, including the overall flush volume and most importantly, for the solid transport on the first flush, the solid position in the appliance discharge.