A study of the litter loadings in urban drainage systems - methodology and objectives

The recently completed report on “The removal of urban litter from stormwater conduits and streams” (by Armitage et al.) notes that little data is available on the nature and quantity of litter that finds its way into the stormwater drainage systems. The Council for Scientific and Industrial Research (CSIR) estimated in 1991 that 780 000 tonnes of waste a year was entering the drainage systems of South Africa, representing a potential removal cost in excess of two billion rand. There is thus a considerable need for finding ways to reduce litter loadings through better catchment management. Although suggestions have been made as to how this might be achieved, there is very little scientifically verified data from anywhere in the world to show that any of these proposed methods would be effective in South Africa. Only through an improved knowledge of the litter loadings in South African urban drainage systems can appropriate strategies to reduce litter loadings be arrived at. This improved knowledge is one of the twin objectives of the Water Research Commission Project No. K5/1051 entitled “The reduction of urban litter in drainage systems through integrated catchment management.” Under this project a three-year monitoring programme has been instituted in nine catchments covering a range of different land uses, socio-economic levels and densities in the Cape Metropolitan Area. This paper focuses on the methodology behind the monitoring programme and the objectives it is hoped to achieve.