Alexandra Settlement

(Case Studies)

The township of Alexandra (Figure 15), located outside of Johannesburg, South Africa, is a prime example of an informal settlement that suffers from issues caused by stormwater runoff and flooding. With a population estimate of 180,000 to 750,000 people, it is severely overpopulated. Overpopulation has led to a multitude of problems including sewage blockages and overflows, as well as problems arising in water pressure and limited flood maintenance(Project Spotlight, 2000).The settlement’s layout exacerbates the problems; the rock and silt that the settlement is built on does not accommodate large quantities of water very easily. Bodies of water surrounding the settlement, such as the Juskei River, are greatly impacted by erosion and sedimentation created by the structure of the land that also depletes the dissolved oxygen content in the environment and reduces the overall biodiversity of the area (Owusu-Asante, 2009).

Figure 1.1: Township of Alexandra

Stormwater drains that are installed throughout the settlement consist of culverts and a network of underground pipes. The pipes connect to a main drainage system that empties into the Jukskei River (Owusu-Asante, 2009). The current setup’s major problem is the merging of sewage and grey-water drainage systems. Consequently, backlogs are created within the sewage systems and by the time they are emptied into the river, the amount of pollution build up is highly extensive. Increased levels of nitrogen, phosphorous and lead that pose a dangerous risk for the health and safety of the settlement’s residents have been documented (Owusu-Asante, 2009).

Researchers have determined that the first and most important objective to generate a solution for this issue regarding stormwater management is to identify the origin of the problem. Studies in Alexandra conclude that overcrowding accounts for the majority of these issues, and the focus on any stormwater management plan should be on relocating residents to sites that do not block maintenance facilities or tributaries in which water could be directed to (Project Spotlight, 2000). While this plan seems to be a simple solution to a large, complicated problem, the successful relocation ofa large number of impoverished people, with a traditional and cultural connection to their residence, is not an easy task. Researchers from the University of the Witwatersrand devised a general management plan for the settlement and broke it into smaller parts to make it more feasible. They began by conducting a desk-top study to research existing reports and studies on stormwater management and other similar topics that could provide useful and relevant information. Then they conducted inspections of the Alexandra Township and monitored the current water flows and other attributes associated with the stormwater drains and sewage systems. They then conducted interviews with the local residents to gain a better understanding of the community issues connected to stormwater and pollution (Owusu-Asante, 2009). Lastly, they involved the community by including them directly in the project on a personal level, thus significantly reducing the risks of community disruption towards the project(Project Spotlight, 2000).

After gathering the necessary information, researchers, engineers, and volunteers began to pinpoint specific stormwater management and sanitation concerns that arose from the township’s overcrowding. These issues expressed from these anxieties were the underlying causes that created a foundation for the more general stormwater and sanitation concerns (Figure 16). From an institutional aspect, they determined that the overpopulation led to the informality of the settlement, and that the lack of available funding resulted in the inability to provide appropriate drainage services. The social conditions of the local residents were also identified as major underlying causes. High unemployment rates and low-living standards were witnessed to lead to the non-payment of basic services as well as the vandalism and improper use of the systems already in place (Owusu-Asante, 2009).

Figure 1.2: Problem Analysis and/or Management Interventions and their Linkages

Five interventions were generated by the researchers involved in this project to focus on the stormwater and waste stream issues which included; downspout disconnection, riparian buffers, impervious cover reduction, rainwater tanks, and stormwater exfiltration systems.  Each intervention was modeled and evaluated based on cost, time, effectiveness, and long term sustainability.  The evaluation process was conducted using a unique “trial and error” strategy thatgave the researchers flexibility and an open mind when testing alternative designs.  The Simple Modeling Method, a technique of estimating pollution masses involved with stormwater runoff using various chemical and mathematical formulas, was used to analyze the annual average pollution load of stormwater in Alexandra.  Once all the research and data had been collected, it was determined that the most beneficial intervention would be the implementation of an exfiltration system (Figure 17).  Like the other designs proposed by the engineers, the installation of the exfiltration systems would be time consuming, taking approximately 15 years to complete (Owusu-Asante, 2009).

Figure 1.3: Cross Section of Exfiltration System

The stormwater project in Alexandra demonstrated the difficulty researchers face when working in an informal settlement.  Not only must they make considerations for the impoverished environment and subsequent cost calculations, they must also identify the numerous underlying causes of the problem that could be related to both the social and political structure within the settlement.

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