Conference Agenda

Retention ponds are highly regarded among Sustainable Drainage Systems (SuDS) for their ability to simultaneously manage flood peaks as well as provide a degree of water quality improvement. It is essential that water quality improvement be reliably modelled by stormwater software. Many factors play a role in the removal of pollutants in retention ponds, but it is likely that the most significant is the hydraulic retention time (HRT). Seven retention ponds have been selected for study across three sites in Cape Town, South Africa: five at the Greenbay Eco Estate, one at the Fynbos Lifestyle Estate and one next to Paddocks Shopping Centre in Milnerton. These ponds predominantly serve middle- to upper-income residential areas, each having moderate to low quality inflows which subsequently discharge into downstream natural environments. This study aimed to develop appropriate methods for data collection and used these to monitor the treatment levels in each of these ponds on a continuous basis over the period of one year. These will be used in the development of retention pond treatment equations for the South African context, where they are severely lacking.