ASPECTS OF SURFACE SEDIMENT CHARACTERISTICS ON AN URBAN CATCHMENT IN LONDON

Initial results of the field trial element of a project concerned with the exclusion and removal of sediments from drainage systems are presented. The trial sites location and characteristics are noted and the sampling and analysis methods described. Results are given for six sites in terms of total dry mass, percentage non-particulate matter, percentage volatile component and sediment gradings. Average total mass figures at 430 g/m kerb are comparable with published figures. Changes over time were negligible at some sites but considerable at others. Non-particulate matter accounted for approximately 3 % by mass with the volatile component at approximately 6%. Consistent sediment gradings were noted at all locations with both sub 63 mum and super 6 mm sizes amounting to approximately 10 % of the total mass. The average specific gravity of the smaller grain sizes was found to be 2.35.