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

The recently completed report on "The removal of urban litter from stormwat er conduits and streams" (by Armitage et al.) notes that little data is ava ilable on the nature and quantity of litter that finds its way into the sto rmwater drainage systems. The Council for Scientific and Industrial Researc h (CSIR) estimated in 1991 that 780 000 tonnes of waste a year was entering the drainage systems of South Africa, representing a potential removal cos t in excess of two billion rand. There is thus a considerable need for find ing ways to reduce litter loadings through better catchment management. Alt hough suggestions have been made as to how this might be achieved, there is very little scientifically verified data from anywhere in the world to sho w that any of these proposed methods would be effective in South Africa. On ly through an improved knowledge of the litter loadings in South African ur ban drainage systems can appropriate strategies to reduce litter loadings b e arrived at. This improved knowledge is one of the twin objectives of the Water Research Commission Project No. K5/1051 entitled "The reduction of ur ban litter in drainage systems through integrated catchment management." Un der this project a three-year monitoring programme has been instituted in n ine catchments covering a range of different land uses, socio-economic leve ls and densities in the Cape Metropolitan Area. This paper focuses on the m ethodology behind the monitoring programme and the objectives it is hoped t o achieve.