Near bed solids transport in sewers

Abstract

This paper describes the results of three sewer sediment studies, carried out in Dundee, financed by the Engineering and Physical Sciences Research Council (EPSRC) and the Water Research centre (WRc). The work was carried out by the University of Abertay Dundee (Wastewater Technology Centre) as part of a collaborative research project undertaken with the University of Newcastle and the University of Sheffield. In Dundee, through collaboration with the sewerage system operator (Tayside Regional Council Water Services Department), three field sites have been established in interceptor and trunk sewer sites, since 1992, to monitor, as closely as possible, sediment and other pollutant erosion, their transport and the effects of first flushes. The physical and biochemical nature of the material being transported near the bed of real sewers has been measured. The importance of this mode of transport, in terms of mass transported and pollutant potential, is demonstrated based on data collected from the Dundee system sites. Comparisons are made between measured transport rates at the bed, at sites with and without deposited beds, with results obtained by applying empirical relationships developed to predict near bed transport in laboratory studies. A modified relationship is proposed which best fits the Dundee system data.