Sediment movement in sewers - interim report

Following from earlier work on sediment in sewers carried out at the Hydraulics Research Station (HRS), a new programme of work, funded by Construction Industry Directorate of Department of the Environment (DoE), is under way at Hydraulics Research (HR). A 300mm diameter concrete pipe is being studied with a 0.72mm sand, at concentration up to the limit of deposition, over a range of flow velocities from 0.5 to 1.3m/s. Pipe-full and part-full conditions are being studied, and head-loss due to the presence of the sediment is being measured. In this report the experimental rig and methodology are described in detail, and data so far collected at the limit of deposition are compared with existing formulae. Measured values of hydraulic gradient without sediment present are analysed to assess the effect of shape factor on resistance. Measured values of velocity at the threshold of movement are compared with existing theories