Gauteng City-Region Observatory (GCRO)
University of the Witwatersrand
Water, Amenities, Sanitation Services and Upgrading Programme (WASSUP)
Local Community Members
Diepsloot – an informal settlement in the north of Johannesburg – has witnessed a rapid population increase over the past 3 decades, and mounting pressure on inadequate existing infrastructure. Haphazard dumping of waste has blocked drains, leading to poor surface drainage, flooding, erosion and dwelling collapse. In response to this challenge, Anne Fitchett (University of the Witwatersrand), Lerato Monama (WASSUP), andJennifer Van Den Bussche (Sticky Situations) designed and implemented an action research project to test a network of sustainable urban drainage systems (SUDS) to improve the surface water quality and drainage regime in Diepsloot. They had previous experience in Diepsloot, and responded to a Gauteng City-Region Observatory (GCRO) call for proposals to demonstrate how green infrastructure could be integrated into informal settlements. With funding support from GCRO, they engaged with locals to implement soak-away pits, semi-permeable drains and permeable paving across two sites, to filter wastewater and improve surface flow.
Two sites were selected for the SUDS interventions in Diepsloot, based on previous experience in the area. This was followed by a survey carried out with potentially affected households to assess interest and level of engagement, and to discuss existing storm water infrastructure and the potential location of new elements. Residents were equally engaged regarding sourcing of materials, facilitated by one of the research team members residing in Diepsloot. The first site was cleared of waste, and the team constructed a soak-away pit, semi-permeable drain and permeable paving. The second site involved altering eroded gullies into semi-permeable channels with a soak-away pit, and vegetation was introduced on both sides. Local construction rubble was sourced from landfills in the area, and community members used it to line the channels, soak away pits and drain to prevent them from being clogged with waste. The channels and drains facilitate surface water flow, while the soak-away reduces runoff and erosion and encourages groundwater infiltration. At the second site, surrounding vegetation filters debris and pollutants from the water, and encourages infiltration. Local residents volunteer to maintain and monitor the intervention.
The installation of SUDS infrastructure protects local communities from excessive water runoff, flooding and erosion, and improves water quality in storm water drains. People have also benefited from the repair of a communal tap that ensures regular water access in the community, and the renovation of a community toilet, with its surroundings paved with graded brick that prevents water logging.
The installation of the SUDS infrastructure in Diesploot improves water quality in terms of chemical oxygen demand (the amount of oxygen required for the oxidation of organic and inorganic matter in water) by up to 94%. Ammonium and nitrate concentrations have reduced across both sites. Water runoff has also decreased across both sites, contributing to reduced erosion. Also, the re-use of construction rubble facilitates circular reuse of waste materials from the construction industry to create low-cost infrastructure, and reduces environmental pollution in the process.
The adoption of action research (that aims to contribute to addressing the practical concerns of people and facilitate learning collaboratively in a mutually acceptable way) embedded in adaptive co-management (where the researchers and residents collectively make decisions and learn from their actions) was fundamental to the implementation of the project. Also, the buy-in and engagement of local residents, and valorisation of local materials (which helped to keep costs low) contributed to the successful implementation of SUDS in Diesploot. Funding support from the GCRO also facilitated implementation.
Water quality tests were performed on samples collected before and after the interventions to ascertain the influence of the SUDS considering a range of water quality parameters such as pH, conductivity, nutrients and chemical oxygen demand (COD). A reduction in water runoff and improved water quality was observed in both channels, indicating the effectiveness of SUDS.
The short-term nature of the project, over-reliance on local community support, and lack of institutional and policy frameworks for the management of SUDs infrastructures challenge the long term effectiveness and scaling of the Diepsloot pilot.
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